Microscopic World I. Part A Unit-based exercise. Topic 2. Unit 5 Atomic structure. Fill in the blanks. True or false

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1 Topic 2 Microscopic World I Part Unit-based exercise Unit 5 tomic structure Fill in the blanks 1 ll elements are made of atoms. 2 Elements exist in different states at room conditions. Silver and sulphur are solids ; bromine and mercury are liquids ; chlorine and oxygen are gases. 3 Elements can be classified into three main groups: metals, metalloids and non-metals. 11 ifferent atoms of an element with the same number of protons but different number of neutrons are isotopes. 12 The weighted average relative isotopic mass of all the naturally occurring isotopes of an element on the 12 = scale is the relative atomic mass of that element. 13 The way in which electrons are arranged in an atom is its electronic arrangement. 14 The electronic arrangement of an atom can be represented by an electron diagram. Part Unit 5 4 The melting and boiling points of non-metals are usually low. 5 Metals are usually good conductors of heat and electricity. 6 oron, silicon and germanium are metalloids. 7 toms consist of a nucleus in the centre and a cloud of electrons that move in circular orbits called shells. 8 The nucleus of an atom contains two types of particles : protons and neutrons. 9 The number of protons in an atom of an element equals the atomic number of the element. 10 The sum of the numbers of protons and neutrons in an atom equals the mass number of the atom. 15 In a hydrogen atom, the region in which there is 95% chance of finding the electron is called an orbital. True or false ecide whether each of the following statements is true or false. 16 t room temperature and pressure, all F metals are solids. 17 Solid non-metals are usually dull in T appearance. 18 Silicon is a metalloid. T 19 Molten sulphur is a good conductor F of electricity. 20 The symbol of magnesium is Ma. F 1

2 Part Unit 5 21 The atomic number of an element T equals the number of electrons in an atom of that element. 22 n atom of an element must F contain equal number of protons and neutrons. 23 ll atoms contain neutrons. F sodium atom ( 1 1Na) contains 11 neutrons. 25 fluorine atom contains 9 electrons. T 26 Isotopes of an element have the same T number of protons. 27 Isotopes of an element have the same F mass. 28 The atomic number of oxygen is 8. T 29 In an atom, the second electron shell F can hold a maximum of 10 electrons. F 33 Which of the following elements is a solid at room temperature and pressure? l N Ne S 34 Which of the following conbinations is INORRET? Element State at room temperature and pressure rgon gas eryllium liquid alcium solid Phosphorus solid 35 onsider the information below: Element Melting point ( ) oiling point ( ) W X Y Z calcium atom contains 3 occupied F electron shells. Multiple choice questions 31 Which of the following combinations is correct? Element Symbol alcium hlorine h Iron Ir Potassium K 32 Which of the following elements is a gas at room temperature and pressure? arbon Iron Oxygen Silicon Which of the following elements is a gas at 25? W X Y Z 36 The table shows the melting points and boiling points of four substances at 1 atm pressure. Substance Melting point ( ) oiling point ( ) W X Y 7 60 Z Which of the following substances exists as a liquid at 100 and 1 atm pressure? W X Y Z 2

3 37 onsider the following information: Substance Melting point ( ) oiling point ( ) W 50 5 X 4 81 Y Z Which of the following solids is likely to be a metal? W X Y Z 42 Which of the following statements concerning silicon is INORRET? Which of the following substances is / are in liquid state at room temperature and pressure? W only X only X and Z only Y and Z only Properties of silicon are in between metals and non-metals. Silicon is brittle. Silicon can be used to make semiconductors. Silicon is soluble in water. Part Unit 5 38 Which of the following elements is a metal? luminium arbon Germanium Neon 39 Which of the following elements is a metalloid? oron opper Helium Phosphorus 40 Which of the following elements is a nonmetal? a e s Kr 41 onsider the information below: Solid Melting point Electrical conductivity Solubility in water W low non-conducting soluble X high non-conducting soluble Y high good insoluble Z very high non-conducting insoluble 43 Which of the following statements concerning the basic structure of an atom is correct? n atom must have equal numbers of protons and neutrons. The mass of one proton is approximately equal to that of an electron. neutron carries a small negative electrical charge. proton carries a small positive electrical charge. 44 The atomic number of an element X is 10. n atom of X has a mass number 22. Which of the following combinations concerning the atom of X is correct? Number of Number of Number of protons neutrons electrons

4 45 n atom has 28 electrons and 30 neutrons. Which of the following combinations concerning the atom is correct? tomic number Mass number Which of the following atoms are isotopes? I and III II and III I and IV II and IV 50 The following table shows the relative abundance of isotopes of lithium: Part Unit 5 46 Which of the following combinations concerning 51 the atomic structure of the atom 2 3X is correct? Number of Number of Number of protons neutrons electrons Isotope Relative abundance (%) 6 Li Li 92.6 The relative atomic mass of lithium is g g. 47 Which of the following particles contains the 32 same number of neutrons as 1 6S? Na 24 12Mg Si P 48 Which of the following combinations concerning isotopes of an element is correct? Number of Number of Number of neutrons protons electrons different same different same different same different same same same same same 51 Element X has two isotopes, 85 X and 87 X. The table below lists the relative abundance of each isotope. Isotope Relative abundance (%) 85 X X 27.9 What is the relative atomic mass of X? Metal X has three isotopes, 189 X, 190 X and 192 X. The graph below shows the relative abundance of the isotopes. 49 onsider the following information of four atoms: tom tomic number Mass number Number of neutrons I II III IV

5 What is the relative atomic mass of X? The electron diagram of an atom of element X is shown below: 53 Element X occurs in nature as two isotopes, 79 X and 81 X. If the relative atomic mass of X is 79.9, what is the relative abundance of the 81 X isotope? 30.0% 35.0% 40.0% 45.0% 54 The relative atomic mass of potassium is It is NOT a whole number because the mass of electrons has been taken into account. fractional protons exist. fractional neutrons exist. isotopes of potassium exist. 55 The atomic mass of element X is X has two isotopes, 69 X and a X, and the relative abundance of 69 X is 65.0%. What is the value of a? The atomic number of an element X is 15. The electronic arrangement of an atom of X is 2,13. 2,8,5. 2,10,3. 2,4,8,1. 57 Which of the following represents the electronic arrangement of an atom of a metalloid? 2,1 2,2 2,3 2,4 (Only electrons in the outermost shell are shown.) X could be l. P. S. Si. 59 Which of the following descriptions of metals is / are correct? (1) They are all solids at room conditions. (2) They are good conductors of electricity. (3) They are all stored in paraffin oil. (1) only (2) only (1) and (3) only (2) and (3) only 60 Which of the following descriptions concerning non-metals are correct? (1) Their melting points are often low. (2) They are brittle if they are solids. (3) They are poor conductors of heat. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 61 Which of the following statements concerning metalloids is / are correct? (1) ll metalloids are solids. (2) Gallium is a metalloid. (3) Metalloids cannot conduct electricity at room temperature. (1) only (2) only (1) and (3) only (2) and (3) only Part Unit 5 5

6 Part Unit Which of the following statements concerning isotopes of an element is / are correct? (1) They have different number of neutrons. (2) They have different atomic numbers. (3) They have the same mass. (1) only (2) only (1) and (3) only (2) and (3) only 63 onsider the following information concerning atoms P and Q: tom Number of protons Number of neutrons Number of electrons P Q Which of the following statements concerning P and Q is / are correct? (1) P is an atom of a non-metal. (2) Q is an atom of a metal. (3) P and Q are isotopes of the same element. (1) only (2) only (1) and (3) only (2) and (3) only 64 onsider the information below: Particle X Y Z Number of protons Number of electrons Number of neutrons Which of the following statements concerning the particles is / are correct? (1) X and Z have the same mass. (2) X and Y are isotopes. (3) Y and Z have the same electronic arrangement. (1) only (2) only (1) and (3) only (2) and (3) only 65 The atomic number of element X is 15. It has only one isotope with a mass number 31. Which of the following statements concerning X is / are correct? (1) X is a gas at room temperature and pressure. (2) There are 5 electrons in the outermost shell of an atom of X. (3) There are 15 neutrons in the nucleus of an atom of X. (1) only (2) only (1) and (3) only (2) and (3) only 66 n atom of element X has an electronic arrangement 2,8,1. Which of the following statements concerning X are correct? (1) It is a metal. (2) Its atom has 11 protons. (3) Its symbol is K. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) The isotope cobalt-60 ( 2 7o) is used to destroy cancer cells in the human body. Which of the 60 following statements concerning a 2 7o atom are correct? (1) It contains 33 neutrons. (2) It contains 27 protons. (3) The number of electrons it has is different from another isotope of cobalt. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3)

7 irections : Each question (Questions 68 75) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. 1st statement 2nd statement 68 arbon is a solid at room temperature and arbon is a non-metal. pressure. Part Unit 5 69 toms are electrically neutral. toms have the same number of protons and electrons. 70 The number of neutrons and that of protons n atom is electrically neutral. in an atom should be the same. 71 The atomic number of sulphur ( S) is S atom contains 16 neutrons X and 2 6Y are isotopes. 24X and 2 6Y have the same mass number but different atomic numbers. 73 Isotopes of a given element have different Isotopes of a given element have different relative isotopic masses. numbers of neutrons. 74 The relative atomic mass of magnesium is not a Magnesium has isotopes. whole number. 75 Isotopes of an element have the same mass. ll atoms of an element contain the same number of electrons. 7

8 Unit 6 The periodic table Fill in the blanks 13 The reactivity of Group VII elements decreases as we move down the Group. 14 Group 0 elements are called noble gases. Part Unit 6 1 In the periodic table, the elements are arranged in order of increasing atomic number. 2 The vertical columns in the periodic table are groups. The horizontal rows are periods. 3 The number of outermost shell electrons in an atom of an element equals the group number of the element. 4 The number of occupied electron shells in an atom of an element equals the period number of the element. 5 cross a period of the periodic table, the elements change from metals through metalloids to non-metals. 6 Group I elements are called alkali metals. 15 The octet rule states that atoms become stable by having eight electrons in their outermost shells. 16 rgon is used to fill electric light bulbs. 17 When an atom of an element loses one or more electrons, it forms a positive ion. 18 When an atom of an element gains one or more electrons, it forms a negative ion. 19 magnesium atom tends to lose 2 electrons to form an ion. magnesium ion has 12 protons and 10 electrons. 20 nitrogen atom tends to gain 3 electrons to form an ion. nitride ion has 7 protons and 10 electrons. 7 Group I elements are stored in paraffin oil in the laboratory. 8 The reactivity of Group I elements increases as we move down the group. 9 Sodium reacts with water to give hydrogen gas and sodium hydroxide. 10 Group II elements are called alkaline earth metals. 11 Group VII elements are called halogens. 12 There is a gradual change in the intensity of the colour of Group VII elements. hlorine is greenish yellow in colour, bromine is reddish brown in colour while iodine is black in colour. True or false ecide whether each of the following statements is true or false. 21 In the periodic table, the elements are F arranged in order of increasing atomic mass. 22 Group number of an element equals the T number of outermost shell electrons in an atom of the element. 23 Elements in the second period of the T periodic table show a gradual change from having metallic property to having non-metallic property. 8

9 24 cross the third period of the periodic F table, the elements show a gradual increase in the number of occupied electron shells in their atoms. 25 Sulphur belongs to Period 2 of the F periodic table. 26 luminium is a Group III element. T 27 Sodium is an alkali metal. T 28 rgon is a halogen. F 29 Magnesium is an alkaline earth metal. T 30 Neon belongs to Group 0 of the periodic T table. 31 Potassium is stored in paraffin oil in the T laboratory. 32 The melting point of sodium is higher F than that of lithium. 33 eryllium and calcium have the same F chemical properties. 34 romine is a volatile liquid. T 35 Iodine vapour is brown in colour. F 36 The boiling point of halogens increases T as we move down the group l and 37 l have different chemical F properties. 38 helium atom has an octet structure F in its outermost shell. Multiple choice questions 41 Which of the following statements concerning the periodic table is correct? Elements are arranged in order of increasing mass number. The vertical columns are called periods. The horizontal rows are called groups. Non-metals are found on the right. 42 Which of the following statements concerning elements in the same group is correct? Their atoms have the same number of occupied electron shells. They have the same atomic number. Their atoms have the same number of outermost shell electrons. Their chemical properties are the same. 43 Which of the following statements concerning elements in Period 2 of the periodic table is correct? They have similar chemical properties. The atom of each element has 2 outermost shell electrons. The atom of each element has two occupied electron shells. cross the period, the elements change from metalloids to metals. 44 To which group does carbon belong? Group II Group IV Group VI Group 0 Part Unit 6 39 ll Group 0 elements are colourless T gases at room temperature and pressure. 40 n oxygen atom gains 2 electrons to T form a stable oxide ion. 9

10 Part Unit 6 45 The electron diagram of an atom of element X is shown below: X belongs to Group II. Group IV. Group VI. Group n atom of element X has 2 completely filled shells only. X is in Group 0. Group II. Group IV. Group VI To which group does the element 1 5X belong? Group I Group III Group V Group VII 48 Which of the following combinations is correct? Element Group number oron II romine VII hlorine V Silicon III 49 Which of the following pairs of elements belongs to the same group? rgon and neon arbon and chlorine alcium and potassium Magnesium and sodium 50 Lithium and sodium show similar chemical properties because they are both metals. have the same atomic number. have the same electronic arrangement in their atoms. have the same number of outermost shell electrons in their atoms. 51 Which of the following pairs of atomic numbers corresponds to elements with similar chemical properties? 7 and 13 9 and and and Element X and aluminium belong to the same group. The atomic number of X could be To which period does sulphur belong? Period 2 Period 3 Period 4 Period 5 54 Which of the following pairs of elements belong to the same period? rgon and aluminium eryllium and silicon hlorine and nitrogen Phosphorus and oxygen 10

11 55 Elements X and Y are in the same period of the periodic table. Which of the following statements concerning X and Y is correct? They have the same relative atomic mass. Their atoms have the same number of occupied electron shells. Their atoms have the same number of outermost shell electrons. They have similar chemical properties. 56 The atomic number of an element X is 9. Which of the following statements concerning X is INORRET? X is a non-metal. X belongs to Period 2 of the periodic table. X is a gas at room temperature and pressure. X belongs to Group II of the periodic table. 59 Which of the following statement concerning chlorine is correct? It is a reddish brown gas. Its atom has 7 outermost shell electrons. It is used to manufacture sodium chloride. It is more reactive than fluorine. Part Unit 6 60 onsider the following elements: 57 Which of the following statements concerning sodium is correct? It is more reactive than potassium. It gives a lilac flame in flame test. It floats on water. It reacts with water to form oxygen gas. 58 Which of the following graphs can represent the variation of the melting point of the Group I elements, Na, K, Rb and s, with increasing atomic number? Element tomic number W 4 X 11 Y 12 Z 19 Which of the following elements is the most reactive metal? W X Y Z 61 solid element X has a melting point of 650. X conducts electricity and reacts readily with dilute hydrochloric acid to give hydrogen. X is probably a Group II element. Group IV element. Group VI element. Group 0 element. 11

12 Part Unit 6 62 Which of the following statements concerning calcium is correct? It is in Period 4 of the periodic table. It is an alkali metal. It reacts with metals to form salts. It catches fire when reacting with cold water. 63 Which of the following graphs shows the trend in the boiling points of the halogens? 65 rgon is used to fill electric light bulbs because it is cheap. is unreactive. glows when hot. is colourless. 66 Which of the following statements concerning noble gases is INORRET? They are all colourless gases. ll of them have little reactivity. ll of their atoms have 8 outermost shell electrons. Their boiling points increase from helium to argon. 67 and are two noble gases. If the atomic number of is x, then the atomic number of could be x 8. x 2. x x irections: Questions refer to the portion of the periodic table shown below. 64 Which of the following statements concerning chlorine, bromine and iodine is INORRET? They are all coloured substances. They are all poisonous. Their reactivity increases with relative atomic mass. They all react with sodium sulphite solution. 68 Which is the most reactive metal? a b g h 69 Which is a liquid at room temperature and pressure? c d e j 12

13 70 onsider the information below: Element Melting point ( ) ensity (g cm 3 ) Electrical conductivity W good X non-conducting Y good Z good Which of the following is likely to be a Group I element? W X Y Z 71 Rubidium and potassium belong to the same group of the periodic table. The relative atomic mass of rubidium is larger than that of potassium. Which of the following statements concerning rubidium is probably correct? It has a very high melting point. Its atom has 2 outermost shell electrons. It is very hard. It is more reactive than potassium. 72 Strontium and calcium belong to the same group of the periodic table. Which of the following statements concerning strontium is correct? It can be extracted from its ore by physical methods. Its atom has one outermost shell electron. It tarnishes when exposed to the air. It floats on water. 74 Which of the following descriptions for the formation of a stable ion from a magnesium atom is correct? The magnesium atom gains two neutrons. The magnesium atom loses two electrons. The mass number of the magnesium atom decreases by 2. The atomic number of the magnesium atom decreases by Which of the following pairs of species has the same number of electrons? Li + and H O 2 and l Na + and S 2 Ne and F n iron atom 2 6Fe forms a Fe 3+ ion. Which of the following combinations concerning the Fe 3+ ion is correct? Number of Number of Number of protons neutrons electrons X is an element and the X 2+ ion has an electronic arrangement 2,8,8. Which of the following statement concerning X is correct? X is a halogen. X is an alkali metal. X is a transition metal. X is a Period 4 element. Part Unit 6 73 Krypton belongs to the same group as neon in the periodic table. Which of the following statements concerning krypton is INORRET? n atom of krypton has an octet structure in its outermost shell. Krypton belongs to Period 3 of the periodic table. Krypton is a colourless gas at room temperature and pressure. balloon full of krypton falls in the air. 78 n anion carries 1 negative charge. It has 36 electrons. How many protons does the anion have?

14 Part Unit 6 79 M is an element. The M 2+ ion has 34 neutrons and 28 electrons. What is M? Ge Ni Se Zn 80 onsider the following information of particles X and Y : Particles Number of protons Number of electrons Number of neutrons X Y Which of the following statements is correct? X and Y are isotopes. X and Y are atoms of different elements. X is an anion. Y is a cation. 81 In moving from Group I to Group VII across the second period of the periodic table, which of the following statements is / are correct? (1) The elements show a gradual increase in atomic size. (2) The elements change from metallic to non-metallic across the period. (3) The elements show a gradual decrease in melting point. (1) only (2) only (1) and (3) only (2) and (3) only 82 Which of the following descriptions is / are true when going down Group IV of the periodic table? (1) The elements show a gradual increase in relative atomic mass. (2) The elements show a gradual increase in atomic size. (3) The elements show a gradual increase in the number of outermost shell electrons in their atoms. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 83 Element X has an isotope 40 18X. Which of the following statements is / are correct? (1) X is in Period 3 of the periodic table. (2) X is in Group VI of the periodic table. (3) 40 18X has 18 neutrons. (1) only (2) only (1) and (3) only (2) and (3) only 84 There is a gradual change in the properties of alkali metals from lithium to potassium. Which of the following properties are in the order lithium < sodium < potassium? (1) tomic size (2) hemical reactivity (3) Melting point (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 85 Which of the following statements concerning Group II elements is / are correct? (1) Their atoms have 2 outermost shell electrons. (2) They are less dense than water. (3) They are stored in water in the laboratory. (1) only (2) only (1) and (3) only (2) and (3) only 14

15 86 Which of the following statements concerning halogens is / are correct? (1) Their reactivity increases with relative atomic mass. (2) romine is a volatile liquid. (3) Iodine vapour is purple in colour. (1) only (2) only (1) and (3) only (2) and (3) only 87 onsider the following information about three elements, X, Y and Z. Element tomic number X 11 Y 16 Z 17 Which of the following statements concerning X, Y and Z are correct? (1) X, Y and Z belong to the same period of the periodic table. (2) X is an alkaline earth metal. (3) Y and Z are non-metals. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 88 Helium is used to fill airships because (1) its density is very low. (2) it does not burn. (3) the air contains a high percentage by volume of it. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 89 Which of the following statements concerning noble gases are correct? (1) ll noble gases have 8 outermost shell electrons in their atoms. (2) Their relative atomic masses increase down the group. (3) They are all colourless gases at room temperature and pressure. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 90 The atomic number of element X is 12. Which of the following statements concerning X are correct? (1) X tarnishes when exposed to the air. (2) X sinks in water. (3) X is extracted by electrolyzing its molten ore. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 91 aesium (s) is a Group I element. Which of the following statements concerning caesium are correct? (1) It reacts with water to give an alkaline solution. (2) It gives a characteristic flame colour in flame test. (3) Its melting point is less than 100. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Part Unit 6 15

16 Part Unit 6 92 Strontium is a Group II element below calcium in the periodic table. Which of the following statements concerning strontium are correct? (1) It forms an ion carrying two negative charges. (2) It is more reactive than calcium. (3) It reacts with non-metals to form salts. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 93 There is a gradual change in the properties of halogens from chlorine to iodine. Which of the following properties are in the order chlorine < bromine < iodine? (1) Reactivity (2) ensity (3) tomic size (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 94 statine is a Group VII element below iodine in the periodic table. Which of the following statements concerning astatine is / are probably correct? (1) It is colourless. (2) Its atom has 7 outermost shell electrons. (3) It is a solid at room temperature and pressure. (1) only (2) only (1) and (3) only (2) and (3) only 95 The electronic arrangement of an atom of element X is 2,8,18,18,8,2. Which of the following statements concerning X are correct? (1) It is denser than water. (2) It gives a characteristic flame colour in flame test. (3) It reacts with dilute hydrochloric acid to give hydrogen. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 96 Which of the following particles is / are present in a H + ion? (1) Proton (2) Neutron (3) Electron (1) only (2) only (1) and (3) only (2) and (3) only 97 Which of the following statements concerning the formation of an oxide ion from an oxygen atom is / are correct? (1) n oxygen atom and an oxide ion have the same number of occupied electron shells. (2) The atomic number of the oxygen atom increases by 2. (3) The mass number of the oxygen atom increases by 2. (1) only (2) only (1) and (3) only (2) and (3) only 98 Which of the following species has / have the same electronic arrangement as a neon atom? (1) O 2 (2) Li + (3) K + (1) only (2) only (1) and (3) only (2) and (3) only 16

17 99 tom X can form a stable ion X. Which of the following statements is / are correct? (1) Ion X has one more neutron than atom X. (2) oth atom X and ion X have the same nuclear charge. (3) Ion X has one more occupied electron shell than atom X. (1) only (2) only (1) and (3) only (2) and (3) only 100 X, Y and Z are three consecutive elements in the periodic table. X forms a stable anion X, while Z forms a stable cation Z +. Which of the following statements about X, Y and Z is / are correct? (1) X and Z + have the same electronic arrangement. (2) X and Z + have the same number of protons. (3) X, Y and Z belong to the same period. (1) only (2) only (1) and (3) only (1) and (3) only irections : Each question (Questions ) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : Part Unit 6 oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. 1st statement 2nd statement 101 Elements are arranged in order of their atomic tomic numbers are always whole numbers numbers, rather than relative atomic masses, while there are fractional relative atomic in the periodic table. masses. 102 Lithium and neon belong to the same period toms of lithium and neon have the same of the periodic table. number of occupied electron shells. 103 Nitrogen and oxygen belong to the same period Nitrogen and oxygen are colourless gases. of the periodic table. 104 cross the second period of the periodic table, cross the second period of the periodic the elements show a gradual increase in table, the elements show a gradual melting point. increase in the number of occupied electron shells in their atoms. 105 cross the third period of the periodic table, cross the third period of the periodic table, the atomic size of the elements. the metallic character of the elements decreases. 17

18 106 Sodium and potassium show similar chemical toms of sodium and potassium have the properties. same number of outermost shell electrons. 107 The density of Group II elements decreases The reactivity of Group II elements decreases down the group. down the group. 108 The reactivity of halogens increases down the The atomic size of halogens increases down group. the group. 109 The elements in Group 0 of the periodic table The outermost shell of an atom of a are very unreactive. Group 0 element is completely filled. 110 chloride ion and an argon atom show similar chloride ion and an argon atom have the chemical properties. same electronic arrangement. Part Unit 7 Unit 7 Ionic and metallic bonds Fill in the blanks 1 Substances can be classified into groups according to how they conduct electricity. a) Substances which conduct electricity but are not chemically changed during conduction are conductors. b) ompounds which conduct electricity in molten state or aqueous solution and are decomposed by electricity during conduction are electrolytes. c) Substances which do not conduct electricity are non-conductors. 5 sulphate ion is formed from one sulphur atom and four oxygen atoms. The whole group of atoms carries two negative charges. 6 sulphite ion is formed from one sulphur atom and three oxygen atoms. The whole group of atoms carries two negative charges. 7 n aqueous solution of potassium permanganate is purple in colour. This colour comes from the permanganate ions. 8 The green colour of jade is due to the presence of chromium(iii) ions. 9 chemical formula is a way of representing a chemical substance using symbols and figures. 2 When metal atoms combine with non-metal atoms, ionic bonds result. 3 When electricity is passed through molten lead(ii) bromide, lead(ii) ions move towards the negative electrode while bromide ions move towards the positive electrode. 10 metallic bond is a type of bond in which positive metal ions are held together by a sea of mobile electrons. 4 n ion that forms from a group of atoms is called a polyatomic ion. 18

19 True or false ecide whether each of the following statements is true or false. Multiple choice questions 21 Which of the following substances is a nonconductor of electricity? 11 n ionic bond is the strong forces of F attraction between ions of the same charge. lcohol opper Graphite Molten potassium chloride 12 Ionic bond usually occurs when metals F combine. 13 When calcium combines with fluorine, T each calcium atom loses two electrons and each fluorine atom gains one electron. irections: Questions 22 and 23 refer to the following experiment. The circuit shown below is set up and the solid lead(ii) bromide is heated until it becomes molten. 14 Element X (atomic number 11) combines F with element Y (atomic number 16) to form a compound with the chemical formula XY Magnesium combines with oxygen to T form a compound with the chemical formula MgO. Part Unit 7 16 Element X (atomic number 20) reacts T with element Y (atomic number 7) to form a compound with the chemical forumla X 3 Y The chemical formula of the compound F formed between astatine (t) and potassium is Kt n aqueous solution of iron(ii) sulphate is F yellow-brown in colour. 19 n aqueous solution of potassium T dichromate is orange in colour. 22 Which of the following statements concerning the experiment is INORRET? The bulb lights up. Nichrome wires can be used as electrodes. reddish brown gas is evolved at electrode Y. The experiment should be carried out in a fume cupboard. 20 Metallic bond is a type of bond in which F positive metal ions are held together by a sea of negative ions. 19

20 23 Which of the following can be deduced from the experimental results? Molten lead(ii) bromide can be decomposed by electricity. Solid lead(ii) bromide is a non-electrolyte. Metallic bonds exist in molten lead(ii) bromide. Solid lead(ii) bromide is a covalent compound but molten lead(ii) bromide is an ionic compound. 27 In which of the following substances do metallic bonds exist? opper opper(ii) sulphate Sodium chloride Silicon 28 Which of the following is an electron diagram of potassium oxide? 24 Which of the following pairs of elements will combine to form an ionic compound? Part Unit 7 opper and magnesium Lithium and sodium Potassium and oxygen Silicon and hydrogen 25 onsider the atomic numbers of four elements. Element a b c d tomic number Which of the following pairs of elements will combine to form an ionic compound? a and b a and c b and d c and d 26 part of the periodic table is shown below. Which of the following elements will combine with element d to form an ionic compound? a b c e 29 Elements X and Y form a compound with the following electron diagram: (Only electrons in the outermost shells are shown.) 20

21 Which of the following combinations is correct? X Y l l a S Li O Mg r 30 The atomic number of element X is 12. X reacts with element Y to form an ionic compound with the chemical formula XY 2. To which group of the periodic table does Y belong? Group II Group V Group VI Group VII 31 The atomic number of element X is 11. X reacts with element Y to form an ionic compound with the chemical formula X 2 Y. To which group of the periodic table does Y belong? Group I Group IV Group VI Group VII 32 Elements X and Y belong to the first three periods of the periodic table. The compound formed between these two elements has the following electronic structure: X Y n ionic compound has the chemical formula XY where X and Y represent the cation and anion respectively. If both X and Y have the same electronic arrangement, the compound may be aluminium oxide. magnesium oxide. lithium fluoride. sodium chloride. 34 The atomic number of an element X is 7. What is the chemical formula of the compound formed between magnesium and X? MgX MgX 2 Mg 2 X 3 Mg 3 X 2 35 n atom of element X has 13 protons while an atom of element Y has 8 electrons. What is the chemical formula of the compound formed between X and Y? XY XY 3 X 2 Y 3 X 3 Y 2 36 Elements X and Y form a compound with the following electronic structure: Part Unit 7 (Only electrons in the outermost shells are shown.) How many electrons are there in the outermost shell of an atom of X and that of Y? (Only electrons in the outermost shells are shown.) 21

22 Part Unit 7 Which of the following combinations is correct? X Y H Li N Mg l Na O 37 Which of the following pairs of elements would react with each other most vigorously? hlorine and lithium hlorine and potassium Fluorine and lithium Fluorine and potassium 38 onsider the information given in the table below: Element tomic number w 9 x 14 y Which of the following ions is responsible for the greenish blue colour of turquoise? opper(ii) ion ichromate ion Iron(III) ion Manganese(III) ion 42 Which of the following ions is responsible for the purple colour of amethyst? u 2+ Fe 2+ Mn 3+ Ni Which of the following solids dissolves in water to form a colourless solution? rl 3 ul 2 Fel 3 Znl 2 44 The table below shows the colours of the aqueous solutions of three ionic compounds: z 20 ompound olour of aqueous solution Which of the following pairs of elements would react with each other most readily? w and y w and z x and y x and z 39 Which of the following ions is a polyatomic ion? mmonium ion hloride ion Magnesium ion Sulphide ion 40 Which of the following compounds, when dissolved in water, gives a green solution? WZ XY XZ blue orange colourless Which of the following combinations about the colours of the ions involved is most likely to be correct? W 2+ (aq) X 2+ (aq) Y 2 (aq) Z 2 (aq) lue orange orange blue lue colourless orange colourless olourless colourless colourless colourless olourless orange colourless blue obalt(ii) chloride Magnesium chloride Nickel(II) sulphate Potassium permanganate 22

23 45 drop of potassium permanganate solution is placed in the centre of the moistened filter paper. d.c. power supply is then applied. Within a few minutes, a coloured patch develops near the positive electrode. 49 The chemical formula of calcium phosphate is a(po 4 ) 2. a(po 4 ) 3. a 2 (PO 4 ) 3. a 3 (PO 4 ) M is an element in the third period of the periodic table. M forms a sulphate with the chemical formula M 2 (SO 4 ) 3. The chemical formula of the chloride of M is What is the colour of the patch? lue rown Orange Purple 46 Element X forms a compound having the chemical formula K 2 X 2 O 7. X could be Ml 2. Ml 3. M 2 l. M 2 l The chemical formula of thorium hydroxide is Th(OH) 4. The chemical formula of thorium permanganate is likely to be ThMnO 4. Th(MnO 4 ) 2. Th 4 MnO 4. Th(MnO 4 ) 4. Part Unit 7 r. F. Mg. S. 47 How many elements does ammonium sulphate consist of? Rubidium (Rb) is in the same group as sodium. What is the chemical formula of rubidium carbonate? RbO 3 Rb(O 3 ) 2 Rb 2 O 3 Rb 3 (O 3 ) 2 52 Strontium (Sr) belongs to Group II of the periodic table. Which of the following statements concerning strontium is correct? Strontium is an alkali metal. Strontium is less reactive than calcium. The chemical formula of strontium chloride is Srl. The density of strontium is higher than that of sodium. 53 statine (t) is a Group VII element. Which of the following statements concerning astatine is correct? statine is a solid at room temperature and pressure. statine is more reactive than chlorine. statine is in Period 4 of the periodic table. The formula of the compound formed between astatine and calcium is a 2 t. 23

24 54 Element X can form a cation X + with an electronic arrangement 2,8. Which of the following statements concerning X is correct? It is a gas at room temperature and pressure. It is in Period 2 of the periodic table. It reacts vigorously with water. It reacts with oxygen to form a compound with the chemical formula XO Which of the following pairs of elements will combine to form ionic compound(s)? (1) alcium and fluorine (2) Neon and nitrogen (3) Potassium and sodium 58 Rubidium (Rb) is a Group I element below potassium in the periodic table. Which of the following statements about rubidium are correct? (1) Its oxide is a crystalline solid. (2) Metallic bonding exists in it. (3) The chemical formula of its sulphate is Rb 2 SO 4. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 59 arium (a) is a Group II element below calcium in the periodic table. Which of the following statements concerning barium are correct? Part Unit 7 (1) only (2) only (1) and (3) only (2) and (3) only 56 Element X can form a cation X 2+ with an electronic arrangement 2,8,8. Which of the following statements concerning X are correct? (1) It can react with hydrogen to form a compound with the chemical formula XH 2. (2) It is in Period 3 of the periodic table. (3) It burns with a brick-red flame. (1) It forms a stable ion carrying 2 positive charges. (2) It is less reactive than calcium. (3) It forms a sulphide with the chemical formula as. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 60 Strontium (Sr) is a Group II element. Which of the following statements concerning strontium carbonate are correct? (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 57 aesium (s) belongs to Group I of the periodic table. Which of the following statements concerning caesium is / are correct? (1) It reacts with water vigorously. (2) It has a high density. (3) The chemical formula of caesium hydroxide is s(oh) 2. (1) Its chemical formula is SrO 3. (2) It conducts electricity in solid state. (3) It is insoluble in water. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) (1) only (2) only (1) and (3) only (2) and (3) only 24

25 61 The atomic number of element X is 7. Which of the following statements concerning X are correct? 64 onsider the following experiment: (1) X is a gas at room temperature and pressure. (2) X is in Period 3 of the periodic table. (3) X reacts with magnesium to form a compound with the chemical formula Mg 3 X 2. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 62 n ionic compound has the chemical formula X 2 Y where X and Y represent the cation and anion respectively. If both X and Y have the same electronic arrangement, the compound could be (1) lithium oxide. (2) potassium sulphide. (3) sodium oxide. (1) only (2) only (1) and (3) only (2) and (3) only 63 Which of the following ions are green in colour? (1) r 3+ (aq) (2) Ni 2+ (aq) (3) MnO 4 (aq) (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Which of the following statements concerning the experiment are correct? (1) green colour gradually develops near electrode X. (2) Gas bubbles are evolved at electrode Y. (3) The experiment can be used to show that ions migrate towards oppositely charged electrodes. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 65 Which of the following statements about the metallic bonding in a solid are correct? (1) The solid contains a regular arrangement of positive ions. (2) Outermost shell electrons of atoms are delocalized throughout the solid. (3) This type of bonding exists in some ionic compounds. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Part Unit 7 25

26 irections : Each question (Questions 66 70) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. 1st statement 2nd statement 66 n oxide ion is very stable. n oxide ion has an electronic arrangement similar to that of a noble gas atom. Part Unit 7 67 toms of helium and neon have 8 outermost Helium and neon are noble gases. shell electrons. 68 Magnesium is in Period 2 of the periodic table. toms of magnesium form ions carrying two positive charges. 69 Element X (atomic number = 20) reacts Each atom of X loses two electrons and each with element Y (atomic number = 7) to form atom of Y accepts three electrons to form a an ionic compound. compound with the chemical formula X 3 Y metal M which forms a chloride Ml 3 must Only metals in Group III of the periodic table belong to Group III of the periodic table. form ions with three positive charges. 26

27 Unit 8 ovalent bonds Fill in the blanks 1 covalent bond is formed when one or more pairs of outermost shell electrons are shared between two atoms. 2 The pair of electrons shared between two atoms is called bond pair electrons. 3 The pair of electrons in the outermost shell of an atom that is not involved in bonding is called lone pair electrons. 4 Each hydrogen molecule consists of two hydrogen atoms. Hydrogen forms diatomic molecules. True or false ecide whether each of the following statements is true or false. 11 In a molecule, the pair of electrons in T the outermost shell of an atom that is not involved in bonding is called lone pair electrons. 12 Nitrogen exists as triatomic molecules. F 13 arbon combines with silicon to form a T covalent compound. 14 Neon and nitrogen combine to form a F covalent compound. 15 The total number of electrons in a water F molecule is 8. 5 molecule which consists of one atom only is called a monoatomic molecule. 6 In a hydrogen chloride molecule, the hydrogen atom contributes one electron(s) for bonding. 7 In an ammonia molecule, the nitrogen atom has three bond pair(s) and one lone pair(s) of electrons. 8 In a Pl 3 molecule, the phosphorus atom contributes three electron(s) for sharing. 9 dative covalent bond is a covalent bond in which the bond pair electrons are provided by the same atom. 16 In a Sil 4 molecule, the silicon atom T contributes 4 electrons for bonding. 17 Iodine and oxygen have the same T bonding type. 18 Hydrogen chloride and siliver chloride F have the same bonding type. 19 Phosphorus combines with hydrogen to F form a compound with the chemical formula PH ovalent bonds exist in ammonium T chloride. Part Unit 8 10 When an ammonia molecule and a hydrogen ion combine to form an ammonium ion, the nitrogen atom supplies its lone pair electrons to the hydrogen ion. 27

28 Multiple choice questions 21 Element X (atomic number = 7) exists as molecules X 2. Which of the following is the electron diagram of a molecule of X? (Only electrons in the outermost shells are shown.) Which of the following pairs of elements will combine to form a covalent compound? a and c a and d b and c b and d 26 The following diagram represents the particles in an element. Part Unit 8 22 n element exists as diatomic molecules. The atomic number of the element could be In which group of the periodic table is this element likely to be found? II III IV V 23 Which of the following pairs of elements will combine to form a covalent compound? Lead and bromine Potassium and chlorine Sodium and hydrogen Sulphur and oxygen 27 Which of the following diagrams best represents the electron diagram of a compound formed between nitrogen and fluorine? (Only electrons in the outermost shells are shown.) 24 Which of the following pairs of elements will combine to form a covalent compound? Lithium and nitrogen Mercury and fluorine Neon and nitrogen Fluorine and chlorine 25 onsider the atomic numbers of four elements. Element a b c d tomic number

29 29 Which of the following substances exists as atoms at room temperature and pressure? mmonia Hydrogen Neon Nitrogen 30 The atomic number of an element X is 16. The chemical formula of the compound formed between chlorine and X is Xl. Xl 2. X 2 l. X 2 l The electron diagram of the compound formed between elements X and Y is shown below: 28 Which of the following electron diagrams is correct? (Only electrons in the outermost shells are shown.) (Only electrons in the outermost shells are shown.) How many outermost shell electrons are there in an atom of X? Part Unit 8 32 The electron diagram of a compound formed between elements X and Y is shown below: (Only electrons in the outermost shells are shown.) Which of the following combinations concerning X and Y is correct? X Y arbon sulphur Silicon oxygen Oxygen lithium Oxygen fluorine 29

30 33 The electron diagram of a compound formed from element X and hydrogen is shown below: (Only electrons in the outermost shells are shown.) How many electrons are there in the outermost shell of an atom of X? Element X can form an anion X 3 with an electronic arrangement 2,8. Which of the following statements concerning X is correct? It is in Group III of the periodic table. It is a solid at room temperature and pressure. It exists as diatomic molecules. It can react with fluorine to form an ionic compound. 38 Which of the following electron diagrams is correct? (Only electrons in the outermost shells are shown.) Part Unit 8 34 Which of the following molecules contains three pairs of bond pair electrons? 2 H 4 O 2 H 2 S Pl 3 35 Which of the following molecules has two pairs of lone pair electrons on the underlined atom? H 4 HN NH 3 Sl 2 36 Elements X and Y have 5 and 7 outermost shell electrons in their atoms respectively. Which of the following combinations concerning the compound they form is correct? hemical formula Type of bond XY 3 covalent X 3 Y covalent X 3 Y ionic XY 3 ionic 39 In which of the following groups of substances there exists a difference in bonding type among the substances? luminium, mercury, sodium alcium chloride, hydrogen chloride, silver chloride arbon dioxide, nitrogen, oxygen Iodine, methane, sulphur dioxide 30

31 40 X is an element in the third period of the periodic table. The chemical formula of the compound formed between aluminium and X is l 2 X 3. Which of the following electron diagrams best represents the compound formed between X and hydrogen? (Only electrons in the outermost shells are shown.) H H X H H X H H H What would be the chemical formula of the compound formed between X and calcium? ax ax 2 a 2 X 3 a 3 X 2 42 onsider the elements from lithium to fluorine in the second period of the periodic table. Which of the following statements is correct? They show a gradual change from having metallic property to having non-metallic property. They show a gradual increase in the number of occupied electron shells in their atoms. They show a gradual decrease in melting point. Their oxides change from covalent to ionic. H X H 43 Which of the following diagrams best represents the arrangement of particles in a metal? Part Unit 8 H X 41 The electron diagram of a compound formed between an element X and chlorine is shown below. (Only electrons in the outermost shells are shown.) 31

32 44 onsider the following table: 47 portion of the periodic table is shown below. Element tomic number Relative atomic mass X Y The formula mass of the compound formed between X and Y is onsider the following table: Which of the following pairs of elements will form covalent compound(s) upon combination? (1) a and f (2) b and d (3) c and e (1) only (2) only (1) and (3) only (2) and (3) only Part Unit 8 Element tomic number Relative atomic mass X Y The relative molecular mass of the compound formed between X and Y is Which of the following molecules have single covalent bonds only? (1) H 4 (2) O 2 (3) H 2 O (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 49 Which of the following molecules contain multiple bond(s)? 46 Which of the following elements can react together to form a covalent compound? (1) Magnesium (2) Phosphorus (3) Oxygen (4) Helium (1) and (2) only (1) and (4) only (2) and (3) only (3) and (4) only (1) O 2 (2) N 2 (3) HN (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 50 Which of the following statements concerning chlorine and bromine are correct? (1) They form ions with 1 negative charge. (2) They exist as diatomic molecules. (3) They can react with sodium sulphite solution. 32

33 (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 53 X and Y are two different elements. The electron diagram of a compound formed between X and Y is shown below: 51 Which of the following statements concerning a methane molecule is / are correct? (1) The number of bonding electrons contributed by each hydrogen atom in the molecule is 2. (2) The number of bonding electrons contributed by the carbon atom in the molecule is 4. (3) The total number of electrons in the molecule is 8. (1) only (2) only (1) and (3) only (2) and (3) only 52 Which of the following electron diagrams are correct? (1) (Only electrons in the outermost shells are shown.) Which of the following statement is / are correct? (1) There are 6 electrons in the outermost shell of an atom of X. (2) There are 8 electrons in the outermost shell of an atom of Y. (3) Each atom of X in the above compound has 4 lone pairs of electrons. (1) only (2) only (1) and (3) only (2) and (3) only 54 X, Y and Z are three different elements. The electron diagram (showing electrons in the outermost shells only) of the compound formed by X, Y and Z is shown below: Part Unit 8 (2) (3) (Only electrons in the outermost shells are shown.) (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Which of the following statments are correct? (1) There is 1 electron in the outermost shell of an atom of X. (2) There are 4 electrons in the outermost shell of an atom of Y. (3) There are 7 electrons in the outermost shell of an atom of Z. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 33

34 55 X, Y and Z are three different elements. The electron diagram (showing electrons in the outermost shells only) of the compound formed by X, Y and Z is shown below: 58 onsider the following elements: Element X Y Z tomic number Part Unit 8 Which of the following statments are correct? (1) There are 2 electrons in the outermost shell of an atom of X. (2) There are 4 electrons in the outermost shell of an atom of Y. (3) There are 7 electrons in the outermost shell of an atom of Z. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 56 Which of the following pairs of elements can form a compound with the chemical formula XY 2? X Y (1) arbon oxygen (2) Lead chlorine (3) Lithium oxygen (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 57 Which of the following bonds exist in ammonium nitrate? (1) ovalent bond (2) Ionic bond (3) Metallic bond (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Which of the following statements concerning the elements are correct? (1) X and Y react to give an ionic compound. (2) X and Z form a compound by electron sharing. (3) Y and Z react to form a compound with the chemical formula YZ. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 59 Which of the following statements concerning elements in the third period of the periodic table are correct? (1) S o d i u m i s m o r e r eactive than magnesium. (2) Phosphorus and chlorine will combine to form a covalent compound. (3) The compound formed between silicon and chlorine has the chemical formula Sil 4. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 60 The atomic numbers of elements X and Y are smaller than 20. X and Y belong to Group IV and VI of the periodic table respectively. Which of the following statements are correct? (1) X tends to form an ion carrying 2 negative charges. (2) Y is a non-metal. (3) X and Y combine to form a covalent compound. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 34

35 irections : Each question (Questions 61 65) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. 1st statement 2nd statement 61 romine and chlorine belong to the same group oth bromine and chloride exist as diatomic of the periodic table. molecules. 62 Neon and nitrogen combine to form a covalent Neon and nitrogen are non-metals. compound. 63 Phosphorus forms a covalent compound with Phosphorus and chlorine belong to the same chlorine. period of the periodic table. 64 When hydrogen combines with chlorine, an uring the reaction, every electron released ionic compound is formed. by a hydrogen atom is accepted by a chlorine atom. Part Unit 8 65 alcium carbonate is a covalent compound. ovalent bonds exist in calcium carbonate. 35

36 Unit 9 Relating the properties of substances to structures and bonding Fill in the blanks 1 Sodium chloride has a giant ionic structure. 2 iamond has a giant covalent structure. 3 Iodine has a simple molecular strcuture. 12 Metals are good conductors of electricity due to the movement of mobile electrons. True or false ecide whether each of the following statements is true or false. 13 Quartz and graphite are allotropes. F 14 The strcuture of silicon is similar to that T of diamond. Part Unit 9 4 Magnesium has a giant metallic structure. 5 Ionic compounds are usually soluble in water but insoluble in non-aqueous solvents. 6 Molten ionic compounds can conduct electricity because they contain mobile ions. 7 llotropes are two (or more) forms of the same element in which the atoms or molecules are arranged in different ways. 8 In a quartz crystal, each silicon atom is joined to four oxygen atoms by covalent bonds, while each oxygen atom is joined to two silicon atoms. 9 In graphite, the cabon atoms are arranged in flat layers. Within each layer, each carbon atom is joined to three carbon atoms by covalent bonds. Van der Waals forces exist between the layers. 15 Silicon carbide (Si) has a simple F molecular structure. 16 Silane (SiH 4 ) has a simple molecular T structure. 17 arbon disulphide (S 2 ) has a giant F covalent structure. 18 Sugar has a simple molecular structure. T 19 opper has a giant metallic structure. T 20 Ionic compounds conduct electricity in F solid state. 21 Sodium chloride is hard due to the strong T ionic bonds between the ions. 22 The melting point of diamond is higher F than that of graphite. 23 In quartz, van der Waals forces hold the F atoms together. 10 Substances with simple molecular structures are usually slightly soluble or insoluble in water but very soluble in non-aqueous solvents. 11 romine has a simple molecular structure. The atoms in each molecule are held together by a covalent bond. The separate molecules are held together by van der Waals forces. 24 Graphite has a slippery feel. T 25 iamond is harder than graphite. T 26 Graphite is used as electrodes in dry T cells. 27 In dry ice, the carbon dioxide molecules F are held together by covalent bonds. 36

37 28 In iodine, the atoms in each molecule F are held together by van der Waals forces. 29 Iodine is very soluble in water. F 30 arbon dioxide and silicon dioxide have F similar physical properties. 31 The melting point of hydrogen chloride is T lower than that of potassium chloride. 32 Silver is a good conductor of electricity T due to the movement of mobile electrons. 35 Which of the following substances is an electrolyte? rgon Potassium Potassium fluoride Tetrachloromethane 36 Solid zinc chloride NNOT conduct electricity because it contains molecules. it is a non-electrolyte. it is a covalent compound. it does not contain mobile ions. Multiple choice questions 33 Which of the following terms correctly describes the structure of potassium bromide? Giant covalent structure Giant ionic structure Giant metallic structure Simple molecular structure 34 Which of the following diagrams best represents the giant structure of a sodium chloride crystal? (In these diagrams, represents a Na + ion and represents a l ion.) 37 Ionic compounds have high melting points because the ions are packed in layers. they are insoluble in water. ionic bonds hold the ions together. they contain mobile ions. 38 Magnesium oxide is used to line industrial furnaces because it has a very high melting point. Which type of bond needs to be broken for magnesium oxide to melt? ovalent bond ative covalent bond Ionic bond Metallic bond Part Unit 9 39 Which of the following chlorides has the highest melting point? Hl Kl Sl 2 Pl 3 40 Which of the following substances is the hardest? iamond Steel Graphite Magnesium oxide 37

38 41 Which of the following correctly describes the structure of silicon dioxide? 47 Which of the following substances consists of separate molecules? Simple molecular structure Giant ionic structure Giant covalent structure Giant metallic structure alcium oxide Graphite Iodine Sodium Part Unit 9 42 Quartz has a very high melting point because it is a covalent compound. it has a giant covalent structure. its atoms are held together by strong ionic bonds. it contains molecules held together by strong forces. 43 Which of the following substances is the most stable in moist air? a Na SiO 2 SO 2 44 Graphite can be used as a lubricant. This is because graphite has mobile ions. delocalized electrons. covalent bonds between atoms in the layers. van der Waals forces between the layers of atoms. 45 Which of the following correctly describes the structure of dry ice? Giant covalent structure Giant ionic structure Giant metallic structure Simple molecular structure 48 Which of the following oxides has a simple molecular structure? MgO l 2 O 3 SiO 2 l 2 O 49 In which of the following substances do van der Waals forces exist? Quicklime Silicon Solid carbon dioxide Solid ammonium chloride 50 romine is a liquid at room temperature and pressure because bromine has a giant covalent structure. bromine molecules are diatomic. bromine molecules are held together by weak intermolecular forces only. bromine atoms within the molecules are held by strong covalent bonds. 51 substance melts at 10 and boils at 58. Which of the following statements concerning the substance is probably correct? It has a simple molecular structure. It is insoluble in non-aqueous solvents. It is a gas at room temperature and pressure. It conducts electricity in solid state. 46 Which of the following substances has a simple molecular structure? 52 Which of the following substances is insoluble in water but soluble in non-aqueous solvents? iamond Mercury Nitrogen Quartz ommon salt Sugar Sulphur Sodium nitrate 38

39 53 n element X combines with chlorine to form a compound with a simple molecular structure. The atomic number of X could be The atomic number of element X is 15. It has only one isotope with a mass number 31. Which of the following statements concerning X is correct? X is a gas at room temperature and pressure. The chemical forumla of the hydride of X is XH 3. There are 16 electrons in an atom of X. ovalent bonds hold the molecules of X together. 55 onsider the following information about three elements, X, Y and Z. Which of the following statements concerning X, Y and Z is correct? X has a high melting point. Y has a giant covalent structure. Z gives an apple green flame in flame test. X and Z combine to form a compound with a simple molecular structure. 57 onsider the following substances: carbon dioxide (O 2 ), silicon dioxide (SiO 2 ) and sodium oxide (Na 2 O) The ascending order of the melting points of these substances is O 2 < Na 2 O < SiO 2 O 2 < SiO 2 < Na 2 O SiO 2 < O 2 < Na 2 O Na 2 O < SiO 2 < O 2 irections: Questions refer to the following information of four elements: Element X Y Z tomic number Which of the following statements concerning X, Y and Z is correct? X and Z combine to form a covalent compound. Y has a simple molecular structure. Z exists as a liquid at room conditions. metal cyclinder containing X should bear the following hazard warning label. Element Melting point ( ) oiling point ( ) Electrical conductivity in molten / liquid state W good conductor X non-conductor Y good conductor Z non-conductor 58 Which of the following statements is INORRET? W is a brittle solid. X has a giant covalent structure. Y is a good conductor of heat. Z is a non-metal. Part Unit 9 56 onsider the following information about three elements, X, Y and Z. Element X Y Z tomic number Element Y is likely to be magnesium. mercury. silicon. sodium. 39

40 60 onsider the information below: Substance Melting point ( ) Electrical conductivity Solubility in water W 7 non-conducting slightly soluble X 46 non-conducting insoluble 63 X and Y are elements. The melting points of their chlorides are given below: Element Melting point ( ) hloride of X 82 hloride of Y 808 Part Unit 9 Y 420 conducting insoluble Z 782 non-conducting soluble Which of the substances exists as a simple molecular solid at room temperature? W X Y Z 61 Group I element X forms a compound with a Group VII element Y. Which of the following statements concerning the compound is INORRET? The compound has a giant ionic structure. The compound is a liquid at room temperature and pressure. The chemical formula of the compound is XY. The compound conducts electricity in molten state. Which of the following statements is correct? oth X and Y are non-metals. The chloride of X is an ionic compound. The chloride of Y is a solid at room temperature and pressure. The chloride of Y conducts electricity in solid state. 64 Which of the following substances can conduct electricity in both solid and liquid states? arbon dioxide iamond Magnesium Sodium chloride 65 opper has a high melting point because it is ductile. it contains mobile electrons. it is malleable. metallic bonds hold its particles together. 62 The table below shows the information of two elements. Element Electronic arrangement of atom X 2,8,5 Y 2,7 Which of the following statements concerning the compound Z formed between X and Y is correct? The bonds in Z are formed by electron transfer. Z has a giant structure. Z has a low melting point. The chemical formula of Z is XY Why does a silver wire conduct electricity when it is connected to a battery? Mobile electrons in the metal move. Silver ions move towards the positive terminal of the battery. The silver atoms become ions. The structure of silver breaks down. 67 The table below shows the electrical conductivity of four substances W, X, Y and Z. Substance Solid state Molten state queous solution W X Y 40 Z (insoluble in water)

41 (In the table, and represent can conduct electricity and cannot conduct electricity respectively.) Which of the substances is likely to be a metal? W X Y Z 70 Which of the following substances has / have giant structure(s)? (1) Oxygen (2) Potassium oxide (3) Silicon dioxide (1) only (2) only (1) and (3) only (2) and (3) only irections: Questions refer to the melting points and boiling points of four substances at 1 atm pressure as listed in the table below: Substance Melting point ( ) oiling point ( ) romine 7 59 hlorine Oxygen Hydrogen bromide Which substance exists as a liquid at 50 and 1 atm pressure? romine hlorine Oxygen Hydrogen bromide 71 Which of the following substances can conduct electricity? (1) Graphite (2) Molten zinc chloride (3) Magnesium sulphate solution (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 72 The structure of silicon carbide is shown below: Part Unit 9 69 Which of the following chemical bonds / attractive forces exist(s) in all four substances at 25 and 1 atm pressure? (1) Van der Waals forces (2) Ionic bond (3) ovalent bond (1) only (2) only (1) and (3) only (2) and (3) only Which of the following statements concerning silicon carbide are correct? (1) Its chemical formula is Si 2. (2) It has a high melting point. (3) It is insoluble in water. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 41

42 Part Unit 9 73 Germanium is a Group IV element below silicon in the periodic table. Which of the following statements concerning germanium is / are probably correct? (1) It is a metalloid. (2) It has a high melting point. (3) Its fluoride has a giant covalent structure. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 74 certain form of solid carbon is composed of 60 molecules. Each 60 molecule is formed by 60 carbon atoms bonded together like a football as shown in the diagram below: Which of the following statements is / are correct? (1) The solid is insoluble in water. (2) The solid is harder than diamond. (3) The melting point of the solid is higher than that of graphite. (1) only (2) only (1) and (3) only (2) and (3) only (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 76 Which of the following properties of graphite is / are evidence(s) to support that covalent bonds are strong? (1) It is slippery. (2) It has a high melting point. (3) It can conduct electricity. (1) only (2) only (1) and (3) only (2) and (3) only 77 Element X exists as diatomic molecules. Solid X has a very low melting point. It is insoluble in water but soluble in non-aqueous solvents. X does not conduct electricity. From these information it can be deduced that (1) X has a simple molecular structure. (2) the attractive forces between molecules of X are weak. (3) the attractive forces between the atoms of X are weak. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 78 Refer to the information of some chlorides shown in the following table. hloride Melting point ( ) oiling point ( ) Nal Selenium (Se) is a group VI element of the periodic table. Which of the following statements concerning selenium are correct? (1) Selenium forms a covalent hydride. (2) The chloride of selenium is a solid with a network structure. (3) Selenium forms Se 2 ions when reacted with Group I elements. Mgl Sil

43 Which of the following statements are correct? (1) Silicon tetrachloride is a liquid at room temperature and pressure. (2) Magnesium chloride has a giant ionic structure. (3) oth sodium chloride and magnesium chloride conduct electricity when heated to 750. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 79 The following table shows the melting points of three compounds. ompound Melting point ( ) NaH 800 SiH H 2 S 85 Which of the following statements can be deduced from the above data? (1) NaH is a solid at 700. (2) SiH 4 has a giant covalent structure. (3) H 2 S is a solid at room temperature and pressure. (1) only (2) only (1) and (3) only (2) and (3) only 80 X has a very high melting point and does NOT conduct electricity at room temperature. It may have a (1) giant covalent structure. (2) giant ionic structure. (3) giant metallic structure. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 81 The atomic numbers of two elements X and Y are 19 and 16 respectively. Which of the following statements concerning the compound formed between X and Y are correct? (1) Its chemical formula is X 2 Y. (2) It is very soluble in non-aqueous solvents. (3) It conducts electricity in aqueous solution. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 82 The atomic numbers of elements X and Y are 8 and 9 respectively. They combine to form a compound Z. Which of the following statements concerning Z is / are correct? (1) It has a giant covalent structure. (2) Its chemical formula is XY 2. (3) It is very soluble in water. (1) only (2) only (1) and (3) only (2) and (3) only 83 Metal X reacts with oxygen to form a compound with a chemical formula X 2 O 3. Which of the following statements are correct? (1) The chemical formula of the chloride of X is Xl 3. (2) X 2 O 3 has a giant ionic structure. (3) X 2 O 3 conducts electricity in molten state. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Part Unit 9 43

44 84 onsider the following elements: 85 onsider the following elements: Element tomic number Relative atomic mass P Q Elements P and Q combine to form a compound X. Which of the following statements about X are correct? (1) X is formed by electron sharing. (2) The relative molecular mass of X is (3) X is a solid at room temperature and pressure. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Element tomic number Relative atomic mass P Q Elements P and Q combine to form a compound X. Which of the following statements about X are correct? (1) X is formed by electron transfer. (2) X is a solid at room temperature and pressure. (3) The formula mass of X is (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) Part Unit 9 irections : Each question (Questions 86 95) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. 1st statement 2nd statement 86 ll ionic compounds are soluble in water. The attractive forces between water molecules are similar to ionic bonds. 87 Potassium chloride has a high melting point. The ionic bonds in potassium chloride are strong. 88 Iodine is slightly soluble in non-aqueous solvents. The attractive forces between iodine molecules are much stronger than those between molecules of iodine and non-aqueous solvents. 89 ovalent bonds are weak. Many covalent compounds are gases, liquids or solids with low melting points. 44

45 1st statement 2nd statement 90 oth diamond and graphite conduct electricity. iamond and graphite are allotropes of carbon. 91 The solubility of calcium carbonate in water is alcium carbonate is an ionic compound while much greater than that of ammonia. ammonia is a covalent compound. 92 The aqueous solution of sugar conducts Sugar reacts with water to form ions. electricity. 93 When iodine sublimes, it absorbs heat. Large amount of heat is required to break the strong covalent bonds between iodine atoms. 94 arbon dioxide and silicon dioxide have similar oth carbon and silicon belong to Group IV physical properties. of the periodic table. 95 Metals are good conductors of heat. Metals contain mobile electrons. Part Topic-based exercise Multiple choice questions 1 The following ideas were those underlying John alton s atomic theory, published in Which idea is known to be correct? toms are indivisible. toms are very small. toms of an element are identical. toms of one element always differ in mass from those of another element. 2 The melting and boiling points of three substances X, Y and Z are given in the table below: Y exists in the liquid state. Z exists in the liquid state. X and Y exists in the liquid state. X, Y and Z exist in the gaseous state. 3 The representation K indicates that this atom has 19 protons, 19 neutrons and 20 electrons. 19 protons, 20 neutrons and 19 electrons. 20 protons, 20 neutrons and 19 electrons. 20 protons, 19 neutrons and 20 electrons. Part Substance X Y Z Melting point ( ) oiling point ( ) mixture of the three substances at 110 is allowed to warm up gradually to 70. Which of the descriptions is correct? 4 In which species are the numbers of electrons and neutrons equal? 9 4 e 23 11Na l l 45

46 Part 46 5 M is an element. The M 2+ ion possesses 34 neutrons and 27 electrons. What is M? o u Ga Se 6 sample of krypton consists of 45.0% 84 Kr and 55.0% 86 Kr. The relative atomic mass of krypton is Iodine (relative atomic mass = 126.9) consists of a mixture of two isotopes: 126 I and 127 I. What is the relative abundance of 127 I in iodine? 10.0% 30.0% 70.0% 90.0% 8 and are two halogens. If the atomic number of is x, then the atomic number of could be x 4. x 10. x + 6. x Which of the following pairs of atoms have similar chemical properties? X and 1 0Y X and 1 2Y X and 1 7Y X and 2 0Y 10 Which of the following pairs of elements in Groups I and VII of the periodic table would react with each other most vigorously? Group I Group VII Rb l Rb r Na l Na r 11 Which of the following statements concerning the elements in Group 0 is INORRET? They can be found in the air. Their boiling points increase down the group. They exist in gaseous state at room temperature and pressure. Their atoms have the same number of outermost shell electrons. 12 onsider the following atoms: tom W X Y Z tomic number Number of neutrons Which of the following statements is INORRET? W and Y belong to the same period. X and Z have similar chemical properties but different physical properties. W is a gas at room temperature and pressure. X is a non-metal The number of neutrons in the 3 4Se 2 ion is erium (e) forms the e 3+ ion. The number of electrons in this ion is When an atom of a Group I element X forms an ion, its mass number increases. the charge of the nucleus increases. Its atomic number decreases. the number of occupied electron shells decreases.

47 16 X is an element and the ion X has an electronic arrangement 2,8,8. Which of the following statements concerning X is correct? X is a halogen. X is a transition metal. X is a Group 0 element. X is a Period 4 element. 17 Which of the following compounds contains ions which have the same electronic arrangement? Na 2 O Li 3 N ao Srl 2 18 In the circuit shown below, the bulb does NOT light up. 19 Which of the following diagrams best represents the arrangement of particles in a sample of chlorine at room temperature and pressure? 20 The electron diagram of a compound formed between magnesium and element X is shown below. Which of the following changes would cause the bulb to light up? dd more solid copper(ii) chloride to the beaker. dd water to dissolve the solid copper(ii) chloride. Replace the carbon electrodes with copper electrodes. Reverse the connections to the electrodes. What would be the chemical formula of the compound formed between X and chlorine? Xl 2 Xl 3 X 2 l 3 X 3 l 2 21 Element E forms a sulphate with the chemical formula E 2 (SO 4 ) 3. Element Z forms a molecular hydride with the chemical formula H 2 Z. The chemical formula of the compound formed from E and Z is likely to be EZ EZ 2 E 2 Z 3 E 3 Z 2 Part 47

48 22 X, Y and Z are three different elements. compound formed between these elements has the following electronic structure: 25 The table below shows the colour of the aqueous solutions of three ionic compounds. ompound WX YX olour of aqueous solution green colourless Part (Only electrons in the outermost shells are shown.) How many electrons are there in the outermost shell of an atom of Y? Element X forms an anion X 3 with an electronic arrangement 2,8. Which of the following statements concerning X is correct? 24 It is in Group III of the periodic table. It is a solid at room temperature and pressure. It exists as diatomic molecules. It can react with neon to form a covalent compound. YZ purple Which of the following combinations about the colours of the ions involved is most likely to be correct? W 2+ (aq) X 2 (aq) Y 2+ (aq) Z 2 (aq) olourless green purple colourless olourless colourless colourless colourless Green colourless colourless purple Green green purple purple 26 onsider the information below: Solid W X Melting point very high very low Electrical conductivity Solubility in water insoluble soluble nonconducting nonconducting Y high nonconducting soluble Z high good insoluble colour moved towards the right in the above set-up. The coloured crystal on the filter paper could be copper(ii) sulphate. potassium chromate. sodium permanganate. zinc sulphate. Which of the following solids is likely to be zinc chloride? W X Y Z 27 Which of the following solids has a low melting point and a high electrical conductivity? Iodine Potassium Potassium fluoride Silicon dioxide 48

49 28 Which of the following statements concerning carbon dioxide is correct? Solid carbon dioxide has a covalent network structure. arbon dioxide is used to fill weather balloons. arbon dioxide dissolves in water to give an acidic solution. arbon dioxide and silicon dioxide have similar physical properties. 29 Which of the following substances has the highest melting point? Methane Sodium Silicon Sulphur 33 n element (melting point above ) forms an oxide which is a gas at room temperature. What type of structure is likely to be present in the element? Ionic Metallic ovalent molecular ovalent network 34 Which of the following chlorides is most likely to be soluble in tetrachloromethane, l 4? arium chloride aesium chloride alcium chloride Phosphorus trichloride 35 The physical properties of three substances X, Y and Z are shown below. 30 Which of the following statements concerning van der Waals forces is correct? They exist in diamond. They exist in limestone. They exist in dry ice. They exist in solid ammonium nitrate. Substance Melting point ( ) oiling point ( ) Electrical conductivity in solid state in molten state X poor good Y poor good 31 In which of the following groups of substances there exists a difference in bonding type among the substances? arium fluoride, magnesium fluoride, potassium fluoride arbon monoxide, sulphur dioxide, methane hromium, magnesium, nickel oron trichloride, silicon tetrachloride, sodium chloride. Z good not known What could be the identities of X, Y and Z? X Y Z NaF Kl Fe Nar ao SiO 2 Nal MgO (graphite) Nar ao (diamond) Part 32 Which of the following chlorides has the lowest boiling point? Hl Kl ll 3 l 4 49

50 36 onsider the following information about four substances, W, X, Y and Z 39 X and Y are elements. The boiling points of their oxides are given below: Substance Melting point ( ) oiling point ( ) Electrical conductivity at room temperature W poor conductor oiling point ( ) Oxide of X 78 Oxide of Y Part X good conductor Y poor conductor Z poor conductor Which substance has a simple molecular structure and is a liquid at room temperature? W X Y Z 37 The atomic numbers of elements X and Y are 8 and 9 respectively. They combine to form a compound Z. Which of the following statements concerning Z is INORRET? Its chemical formula is XY 2. It is formed by electron sharing. Van der Waals forces exist in it. It is a crystalline solid at room temperature and pressure. 38 onsider the following elements: Which of the following statements is correct? X is a metal. The oxide of X is a covalent compound. The oxide of Y is a gas at room temperature and pressure. Van der Waals forces exist in the oxide of Y. 40 gallium isotope Ga can be used to detect tumours. Which of the following statements about this gallium isotope is / are correct? (1) It has 37 neutrons. (2) Its atomic number is 68. (3) Its chemical properties are the same as those of other isotopes of gallium. (1) only (2) only (1) and (3) only (2) and (3) only 41 Which of the following species has (have) an octet structure in the outermost shell(s)? 50 Element tomic number X 14 Y 17 Which of the following statements is correct? X has a simple molecular structure. Y is a volatile liquid. The compound formed between X and Y has a giant covalent structure. The compound formed between X and Y has a low melting point. (1) Li + (2) N 3 (3) r (1) only (2) only (1) and (3) only (2) and (3) only 42 Which of the following statements about the periodic table are correct? (1) The reactivity of Group II elements increases with relative atomic mass. (2) The boiling point of Group VII increases with relative atomic mass. (3) ll elements in Group 0 exist in gaseous state at room temperature and pressure.

51 (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 43 In moving from Group I to Group VII across the third period of the periodic table, which of the following physical properties of the elements show a gradual change? (1) tomic size (2) Metallic character (3) Melting point (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 44 The elements, sodium to chlorine, in the third period of the periodic table show a gradual change in properties. Which of the following descriptions are correct? (1) The number of outermost shell electrons in their atoms increases. (2) Their ability to gain electrons increases. (3) Their chlorides change from covalent to ionic. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 45 small piece of potassium is dropped into a trough of water. piece of red litmus paper is used to test the water after the experiment. Which of the following observations are correct? (1) The potassium moves on the water surface with a hissing sound. (2) The potassium burns with a lilac flame. (3) The water turns the red litmus paper blue. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 46 Which of the following properties of Group II elements increase with relative atomic mass? (1) tomic size (2) Melting point (3) Reactivity with water (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 47 aesium (s) belongs to Group I of the periodic table. aesium reacts with bromine to form a compound. Which of the following statements concerning the compound are correct? (1) Its chemical formula is sr. (2) It is very soluble in non-aqueous solvents. (3) It is a crystalline solid at room temperature and pressure. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 48 Strontium (Sr) is a Group II element. Which of the following statements concerning strontium is / are correct? (1) Strontium does not burn in air. (2) Strontium reacts with water to liberate hydrogen. (3) ll its compounds are coloured. (1) only (2) only (1) and (3) only (2) and (3) only 49 Germanium (Ge) is a Group IV element below silicon in the periodic table. Which of the following statements concerning germanium are correct? (1) It has a giant covalent structure. (2) Its atomic size is larger than that of silicon. (3) Its fluoride has a chemical formula GeF 4. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 51 Part

52 Part 50 Which of the following statements concerning chlorine are correct? (1) It exists as diatomic molecules. (2) It is denser than air. (3) It is used to sterilize swiming pool water. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 51 Which of the following statements concerning halogens are correct? (1) ompounds of fluorine are added to tap water to help prevent tooth decay. (2) romine is a volatile liquid. (3) Iodine can sublime. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 52 Which of the following statements concerning chlorine, bromine and iodine are correct? (1) They are all coloured substances. (2) Their reactivity decreases down the group. (3) Van der Waals forces exist between their molecules. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 53 Hydrogen peroxide (H 2 O 2 ) is an oxide of hydrogen. Which of the following statements concerning a hydrogen peroxide molecule is / are correct? (1) The number of bonding electrons contributed by each hydrogen atom in the molecule is 2. (2) The number of bonding electrons contributed by each oxygen atom in the molecule is 2. (3) The total number of electrons in the molecule is 18. (1) only (2) only (1) and (3) only (2) and (3) only 54 Which of the following bonds or attractive forces exist in calcium carbonate? (1) Ionic bond (2) ovalent bond (3) Van der Waals forces (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 55 Which of the following substances have giant structures? (1) opper (2) Nitrogen dioxide (3) Silicon dioxide (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 56 onsider the following information: Substance ttractions between particles in substance (1) Neon van der Waals forces (2) Zinc metallic bond (3) Magnesium chloride ionic bond Which of the following combinations are correct? (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 52

53 57 In which of the following groups of substances do members have the same bonding type? (1) opper, mercury, tungsten (2) ry ice, nitrogen dioxide, water (3) opper(ii) chloride, hydrogen chloride, zinc chloride (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 58 Which of the following substances contain delocalized electrons? (1) Graphite (2) Methane (3) Sodium (1) only (2) only (1) and (3) only (2) and (3) only 60 onsider the following elements: Element tomic number Relative atomic mass P Q Elements P and Q combine to form a compound X. Which of the following statements about X are correct? (1) X is formed by electron transfer. (2) The relative molecular mass of X is (3) Van der Waals forces exist in X. (1) and (2) only (1) and (3) only (2) and (3) only (1), (2) and (3) 59 Which of the following properties of potassium chloride is / are evidence(s) to support that ionic bonds are strong? (1) It can conduct electricity in molten state. (2) It has a high melting point. (3) It is soluble in water. Part (1) only (2) only (1) and (3) only (2) and (3) only 53

54 irections : Each question (Questions 61 70) consists of two separate statements. ecide whether each of the two statements is true or false; if both are true, then decide whether or not the second statement is a correct explanation of the first statement. Then select one option from to according to the following table : oth statements are true and the 2nd statement is a correct explanation of the 1st statement. oth statements are true but the 2nd statement is NOT a correct explanation of the 1st statement. The 1st statement is false but the 2nd statement is true. oth statements are false. 1st statement 2nd statement 61 Isotopes of an element have the same chemical Isotopes of an element have the same number properties. of outermost shell electrons. 62 rgon is used to fill electric light bulbs. rgon exists as monoatomic molecules. 63 Nitrogen is used to fill the packets of potato Nitrogen is a gas at room temperature and chips. pressure. 64 queous solution of carbon dioxide cannot arbon dioxide is a covalent compound. conduct electricity. 65 Metals are good conductors of electricity. Metals contain mobile electrons. 66 romine is a good conductor of electricity. romine contains mobile bromine molecules. Part 67 ll covalent substances are insoluble in water. ll covalent substances have simple molecular structures. 68 The boiling point of bromine is higher than that The van der Waals forces between bromine of chlorine. molecules are stronger than those between chlorine molecules. 69 The melting point of hydrogen chloride is lower Hydrogen chloride is a covalent compound than that of zinc chloride. while zinc chloride is an ionic compound. 70 In ammonia, the mass of hydrogen is three n ammonia molecule contains one nitrogen times that of nitrogen. atom and three hydrogen atoms. 54

55 Short questions 71 omplete the following table by (12 marks) a) filling in the names or symbols of the elements; b) classifying each element into metal, metalloid or non-metal. Element Symbol Metal / Metalloid / Non-metal rgon r non-metal arbon non-metal alcium a metal Fluorine F non-metal Germanium Ge metalloid Lithium Li metal Magnesium Mg metal Neon Ne non-metal Nitrogen N non-metal Potassium K metal Phosphorus P non-metal Silicon Si metalloid (0.5 x 24) 72 omplete the following table. (20 marks) tom tomic number Mass number Symbol Number of protons neutrons electrons Oxygen O Part 23 Sodium Na luminium l Sulphur S hlorine l Potassium K alcium a Iron Fe (0.5 x 40) 55

56 73 Look at the list of elements. boron chlorine copper fluorine magnesium nickel nitrogen phosphorus nswer the following questions. hoose all your answers from the list. Each element can be used once, more than once or not at all. (6 marks) a) Write down the name of a greenish yellow gas. chlorine (1) b) Write down the name of an element that forms compounds that are blue in colour. copper (1) c) Write down the name of the element whose atom contains 15 protons. phosphorus (1) d) Write down the name of the element whose atom has an electronic arrangement 2,5. nitrogen (1) e) Write down the name of a metalloid. boron (1) f) Write down the name of an element that forms ions which is green in aqueous solution. nickel (1) 74 a) omplete the following table. (20 marks) Part Species tomic number Mass number Number of protons neutrons electrons Electronic arrangement i) eryllium atom ,2 ii) Neon atom ,8 iii) Silicon atom ,8,4 iv) Phosphorus atom ,8,5 v) Potassium ion ,8,8 vi) Nitride ion ,8 vii) Magnesium ion ,8 viii) Fluoride ion ,8 ix) Sodium ion ,8 x) Sodium atom ,8,1 (0.5 x 40) 56

57 b) Which species in the above table is / are negatively charged? (1 mark) Species (vi) & (viii) / nitride ion and fluoride ion (0.5 x 2) c) In which group of the periodic table should species (iii) be placed? Explain your answer. (2 marks) Group IV; (1) it has 4 electrons in its outermost shell. (1) d) State the relationship between species (ix) and (x). (1 mark) Species (ix) is the cation of species (x) / (ix) and (x) are the ion and atom of the same element. (1) 75 a) Write down the chemical formula for each of the following compounds. (8 marks) Name hemical formula luminium hydroxide l(oh) 3 mmonium dichromate (NH 4 ) 2 r 2 O 7 alcium phosphate a 3 (PO 4 ) 2 opper(ii) chloride ul 2 Iron(III) oxide Fe 2 O 3 Magnesium hydroxide Mg(OH) 2 Potassium carbonate K 2 O 3 Sodium sulphite Na 2 SO 3 (1 x 8) b) Write down the names of the following compounds. (8 marks) Part hemical formula KHO 3 Fe 2 (SO 4 ) 3 u(oh) 2 Mg 3 N 2 Zn(NO 3 ) 2 NaS l 2 O 3 Name potassium hydrogencarbonate iron(iii) sulphate copper(ii) hydroxide magnesium nitride zinc nitrate sodium sulphide aluminium oxide gl silver chloride (1 x 8) 57

58 76 omplete the following table. (21 marks) ation nion ompound Name Formula Name Formula Name Formula olour of aqueous solution ammonium NH 4 + carbonate O 3 2 ammonium carbonate (NH 4 ) 2 O 3 colourless copper(ii) u 2+ nitrate NO 3 iron(ii) Fe 2+ sulphate SO 4 2 potassium K + permanganate MnO 4 copper(ii) nitrate u(no 3 ) 2 blue iron(ii) sulphate FeSO 4 pale green potassium permanganate KMnO 4 purple nickel(ii) Ni 2+ chloride l nickel(ii) chloride Nil 2 green aluminium l 3+ iodide I aluminium iodide ll 3 colourless chromium(iii) r 3+ chloride l chromium(iii) chloride rl 3 green sodium Na + dichromate r 2 O 7 2 sodium dichromate Na 2 r 2 O 7 orange zinc Zn 2+ bromide r zinc bromide Znr 2 colourless (0.5 x 42) 77 a) Use an electron diagram to show the electron transfer when each of the following pairs of elements combine, showing electrons in the outermost shells only. (3 marks) i) alcium and chlorine Part (1) 58

59 ii) Magnesium and nitrogen (1) iii) Sodium and sulphur Part (1) b) Use an electron diagram to show the sharing of electrons when each of the following pairs of elements combine, showing electrons in the outermost shells only. (3 marks) i) Phosphorus and chlorine (1) 59

60 ii) Oxygen and hydrogen (1) iii) hlorine and fluorine (1) 78 alculate the formula masses or relative molecular masses of the following substances. (5 marks) Part Substance hemical formula Relative atomic mass(es) Formula mass / relative molecular mass Oxygen O 2 O = = 12.0 arbon dioxide O O = 16.0 Potassium nitrate KNO 3 O = 16.0 N = 14.0 K = 39.1 alcium hydroxide a(oh) 2 O = 16.0 H = 1.0 a = 40.1 Iron(III) sulphate Fe 2 (SO 4 ) 3 S = 32.1 O = 16.0 Fe = (1 x 5) 79 Phosphorus and nitrogen are in Group V of the periodic table and both elements form hydrides. Phosphine, PH 3, reacts to form phosphonium ions, PH 4 +, in a way similar to that by which ammonia, NH 3, forms ammonium ions, NH 4 +. a) Give the name of the type of bond formed when PH 3 reacts with an H + ion. (1 mark) ative covalent bond (1) 60

61 b) Explain how the bond is formed. (2 marks) The phosphorus atom (1) supplies both bonding electrons to the hydrogen ion. (1) 80 rrange the following substances into four groups according to their structures: carbon dioxide, chlorine, copper, copper(ii) sulphate, diamond, magnesium fluoride, nitrogen, quartz, sodium, sodium sulphide (5 marks) Giant ionic structure Giant covalent structure Simple molecular structure Gaint metallic structure copper(ii) sulphate, magnesium fluoride, sodium sulphide diamond, quartz carbon dioxide, chlorine, nitrogen copper, sodium (0.5 x 10) 81 Write down the type of forces of attraction (ionic bond / covalent bond / metallic bond / van der Waals forces) present in each of the following cases: (5 marks) Forces of attraction etween carbon atoms in diamond covalent bond etween carbon dioxide molecules in dry ice van der Waals forces Part etween particles in calcium nitride ionic bond etween particles in magnesium metallic bond etween carbon and oxygen atoms in a carbon dioxide molecule covalent bond (1 x 5) 61

62 82 onsider the following liquids: molten potassium molten sulphur molten potassium chloride liquid hydrogen chloride a) lassify each of the above liquids in one of the following three ways according to its response to a direct current: (4 marks) Non-conductor molten sulphur (1) onductor, with decomposition at the electrodes onductor, but without decomposition molten potassium chloride (1) molten potassium (1) liquid hydrogen chloride (1) b) For each of the above liquids which are conductors, state the particles responsible for the conduction of electricity. (2 marks) molten potassium chloride mobile potassium ions and chloride ions (1) molten potassium mobile electrons (1) Structured questions 83 Silver occurs in nature as two isotopes: 107 g and 109 g. The relative abundance of these isotopes is shown below. Part Isotope Relative abundance (%) 107 g g 45 a) State the meaning of the term relative atomic mass. (2 marks) The relative atomic mass of an element is the weighted average relative isotopic mass of all the naturally occurring isotopes of that element (1) on the 12 = scale. (1) b) alculate the relative atomic mass of silver. (2 marks) 107 x x (1) = (1) 62

63 c) Is it possible to separate the isotopes of silver by chemical means? Explain your answer. (2 marks) Isotopes of silver have the same chemical properties. (1) Hence it is impossible to separate the isotopes of silver by chemical means. (1) 84 Silicon occurs naturally in three isotopic forms. The relative abundance of each isotope is shown in the table below: Isotope 28 Si 29 Si 30 Si Relative abundance (%)?? 3.1 a) State the meaning of the term isotopes. (2 marks) Isotopes are different atoms of an element which have the same number of protons (1) but a different number of neutrons. (1) b) The relative atomic mass of silicon is alculate the relative abundance of the 28 Si isotope. (2 marks) Let the relative abundance of 28 Si and 29 Si be y% and (96.9 y)% respectively. 28 x y + 29 x (96.9 y) + 30 x = 100 (1) y = 94.1 (1) c) Suggest ONE use of silicon. (1 mark) Making semi-conductors (1) Part d) Silicon combines with carbon to form silicon carbide (Si). The structure of silicon carbide is similar to that of diamond. raw the three-dimensional structure of silicon carbide. (2 marks) (1 mark for the correct arrangement of atoms; 1 mark for the correct labelling of silicon and carbon atoms) (2) 63

64 e) Silicon combines with chlorine to form silicon tetrachloride (Sil 4 ). raw an electron diagram of the chloride, showing electrons in the outermost shells only. (1 mark) (1) f) Explain why silicon carbide has a higher melting point than silicon tetrachloride in terms of their structures. (3 marks) Silicon carbide has a giant covalent structure while silicon tetrachloride has a simple molecular structure. (1) To melt silicon carbide, a lot of heat is needed to overcome the strong covalent bonds between the atoms. (1) Weak van der Waals forces exist between molecules of silicon tetrachloride. Little heat is needed to separate the molecules. (1) Part 85 oron occurs naturally in two isotopes. The relative abundance of each isotope is shown in the table below: Isotope Relative abundance (%) a) ompare these two isotopes in terms of the subatomic particles they contain. (2 marks) oth have 5 protons and 5 electrons. (1) 10 has 5 neutrons while 11 has 6 neutrons. (1) OR oth have the same number of protons and electrons. (1) 10 and 11 have different number of neutrons. (1) b) What is the meaning of the term relative atomic mass? (2 marks) The weighted average relative isotopic mass of all the naturally occurring isotopes of that element (1) on the 12 = scale. (1) 64

65 c) alculate the relative atomic mass of boron. (2 marks) 10 x x (1) = 10.8 (1) d) 10 l 3 and 11 l 3 are compounds formed respectively from the two isotopes of boron with chlorine. 10 l 3 reacts with water to give steamy fumes. State, with explanation, the expected observation when 11 l 3 reacts with water. (1 mark) 11 F 3 would give steamy fumes because the chemical propertries of isotopes are the same. (1) e) oron is a metalloid. Suggest ONE physical property of boron. (1 mark) oron is a semi-conductor. (1) f) The equation below shows the reaction between boron trifluoride and a fluoride ion. F 3 + F F 4 i) In terms of the electrons involved, explain how the bond between the F 3 molecule and the F ion is formed. (1 mark) The bond pair electrons are provided by the F ion. (1) ii) Name the type of bond formed. (1 mark) ative covalent bond (1) 86 part of the periodic table is shown below: Part a) What determines the position of an element in the periodic table? (1 mark) Its atomic number (1) b) cross a period, the elements show a gradual change in some of their physical properties. State ONE such property. (1 mark) tomic size / metallic character of elements (1) c) Name TWO elements which are mainly obtained from the sea. (1 mark) Sodium and chlorine (0.5, 0.5) 65

66 d) For each of the following pairs of elements, suggest ONE reaction in which they behave similarly. i) Sodium and potassium (2 marks) Sodium and potassium react with cold water vigorously. (1) Hydrogen is evolved. / n alkaline solution is formed. (1) ii) hlorine and fluorine (1 mark) hlorine and fluorine react with metal to form salts. (1) e) Which metal and non-metal in the above table would react most vigorously with each other? (1 mark) Potassium and fluorine (0.5, 0.5) f) Which element in the third period has the highest melting point? Explain in terms of the structure of the element. (3 marks) Silicon has the highest melting point. (1) Silicon has a giant covalent structure. (1) To melt silicon, a lot of heat is needed to overcome the strong covalent bonds between the atoms. (1) g) The atomic number of krypton (Kr) is 36. The electronic arrangement of a krypton atom is 2,8,x,y. What are the values of x and y? (1 mark) x = 18 (0.5) y = 8 (0.5) Part h) Rubidium (Rb) is a Group I element. Its relative atomic mass is larger than that of potassium. i) Suggest whether rubidium or potassium is more reactive. (1 mark) Rubidium is more reactive. (1) ii) Suggest a method to store rubidium in the laboratory. (1 mark) It should be stored in paraffin oil. (1) 87 With reference to the part of the periodic table shown, answer the following questions. 66

67 a) Name ONE metalloid in the above table. (1 mark) oron / silicon (1) b) Name TWO elements which make up 99% of air. (1 mark) Nitrogen and oxygen (0.5, 0.5) c) Explain why argon is monoatomic. (2 marks) n argon atom has 8 electrons in its outermost shell. special stability is obtained when this happens. (1) n argon has very little tendency to share electrons with other argon atoms. Therefore argon is monoatomic. (1) d) Name the group to which lithium and sodium belong. (1 mark) lkali metals (1) e) In what way are the electronic arrangements of atoms of lithium and sodium i) similar to each other? (1 mark) They have the same number of outermost shell electrons. (1) ii) different from each other? (1 mark) They have different number of occupied electron shells. 1) f) Point out the gradual change in the reactivity of Group II elements down the group. (1 mark) The reactivity of Group II elements increases down the group. (1) g) Suggest TWO gradual changes in the physical properties of Group VII elements down the group. (2 marks) Part There is a gradual increase in the melting / boiling point of the elements. (1) There is a gradual change in the intensity of the colour of the elements. (1) 67

68 h) escribe the structure and bonding in aluminium with the help of a diagram. (3 marks) luminium has a giant metallic structure. It consists of tightly packed positive ions surrounded by a sea of delocalized electrons. (1) The attractive forces between the electrons and positive ions hold the particles of aluminium together. (1) (1) 88 portion of the periodic table is shown below. Part a) How are the elements arranged in the periodic table? (1 mark) Increasing atomic number (1) b) What is the similarity in the electronic arrangement of atoms of elements in the same period? (1 mark) They have the same number of occupied electron shells. (1) c) Which element in Group I has the smallest atomic size? (1 mark) Lithium / Li (1) d) Suggest why Group 0 elements seldom form compounds. (1 mark) toms of Group 0 elements have stable electronic structure. (1) e) i) Which is the most reactive metal in the above table? (1 mark) Potassium / K (1) 68

69 ii) Suggest how the most reactive metal should be stored. (1 mark) It should be stored in paraffin oil. (1) iii) State ONE hazard warning label that should be displayed on a reagent bottle containing that metal. (1 mark) Flammable / corrosive (1) f) Which of the above elements is used to make computer chips? (1 mark) Silicon / Si (1) g) Suggest ONE use of chlorine. (1 mark) Making bleach / hydrochloric acid / organic solvents (1) h) alloons filled with different noble gases were tied to a bar. They were held horizontally at the same height and then released. The positions of two of the balloons 5 seconds after release are shown in the diagram. Predict the position of the balloon filled with krypton (Kr) after 5 seconds. (1 mark) Part Lower than argon (1) 89 The following questions refer to the incomplete periodic table shown below. a) Which of the above elements are metals. (1 mark) f, h (0.5, 0.5) b) List FOUR typical properties of metals. (4 marks) ny four of the following: Melting / boiling point usually high (1) Shiny appearance (1) Good conductor of electricity (1) Good conductor of heat (1) uctile / malleable (1) Lose electrons / form positive ions (1) 69

70 c) How many occupied electron shells are there in an atom of f? (1 mark) 3 (1) d) Which element forms an ion carrying 1 negative charge? (1 mark) d (1) e) Which element has an octet of electrons in the outermost shell of its atom? (1 mark) e (1) f) i) Name the group to which h belongs. (1 mark) lkali metals (1) ii) Suggest TWO safety precautions for handling h in the laboratory. (2 marks) ny two of the following: Wear safety glasses. (1) Use forceps. (1) Use a safety screen. (1) g) Name the group to which e belongs. (1 mark) Noble gases (1) h) Which metal and non-metal in the above table would react most vigorously with each other? (1 mark) d and h (0.5, 0.5) i) b and f can combine to form a compound X. raw an electron diagram of X, showing electrons in the outermost shells only. (1 mark) Part (1) 90 The circuit shown below is set up and the solid lead(ii) bromide is heated until it becomes motlen. 70

71 When the lead(ii) bromide becomes molten, the bulb lights up. a) Suggest a suitable material for making electrodes X and Y. (1 mark) Nichrome / graphite (1) b) What would be observed at electrode X? (1 mark) reddish brown gas evolves. (1) c) What would be observed at electrode Y? (1 mark) white shiny solid deposits on the electrode. (1) d) Suggest a place in the laboratory where this experiment could be carried out safely. riefly explain your answer. (2 marks) Inside a fume cupboard (1) The reddish brown gas (bromine) evolved is toxic. (1) e) State what will happen to the bulb when heating is stopped and the molten lead(ii) bromide is allowed to cool down gradually to room temperature. Explain your answer. (3 marks) The light bulb gradually goes out. (1) s the temperature drops, movement of ions in molten lead(ii) bromide slows down. Therefore a smaller current flows through the external circuit. (1) When the molten lead(ii) bromide becomes solid, there are no mobile ions. Hence no current flows through the external circuit. (1) 91 tiny potassium permanganate crystal was placed at the centre of a piece of filter paper moistened with sodium sulphate solution. d.c. power supply was then applied. Within a few minutes, a coloured patch was seen to develop on the filter paper. Part a) What was the purpose of moistening the filter paper with sodium sulphate solution? (1 mark) For the conduction of electricity (1) 71

72 b) i) What was the colour of the patch developed on the filter paper? (1 mark) Purple (1) ii) Sketch the position where the coloured patch would be expected to develop. (Positive and negative electrodes must be shown.) (2 marks) (2) c) The positive and negative electrodes were then reversed after some time. riefly explain what would be observed. (2 marks) The coloured patch would move towards the new position of the positive electrode (1) because the negative permanganate ions would be attracted towards the positive electrode. (1) 92 The diagram shows an experimental set-up for studying the reaction of lithium with water. Part a) escribe what you would observe when the lithium reacts with the water in this experiment. (3 marks) ny three of the following: Lithium fizzes / produces a gas. (1) The universal indicator turns blue / purple (alkaline colour). (1) The water level in the test tube goes down (or gas fills the test tube). (1) Lithium moves around on the surface of water. (1) Lithium dissolves. (1) 72

73 b) Write a word equation for the reaction of lithium with water. (1 mark) lithium + water lithium hydroxide + hydrogen (1) c) aesium is another Group I element. Suggest whether caesium or lithium is more reactive. (1 mark) aesium is more reactive. (1) d) The graph shows the melting points of the Group I metals plotted against the atomic numbers. i) escribe fully how the melting point changes as the atomic number increases. (2 marks) The melting point decreases as the atomic number increases (1) Part and the rate of decrease slows down. (1) ii) Francium has an atomic number 87. Use the graph to estimate the melting point of francium. (1 mark) 26 (1) e) Elements in Group I can react with elements in Group VII. Look at the four examples below. potassium + iodine lithium + chlorine potassium + chlorine lithium + iodine potassium iodide lithium chloride potassium chloride lithium iodide i) Which of the above reactions is the most vigorous? (1 mark) (1) 73

74 ii) Explain your answer in (i) by describing the reactivity trends in the periodic table. (2 marks) The reactivity of Group I elements increases as we move down the group (i.e. potassium is more reactive than lithium). (1) The reactivity of Group VII elements decreases as we move down the group (i.e. chlorine is more reactive than iodine). (1) 93 The following table lists the atomic numbers of some elements in Group II. Element tomic number e 4 Mg 12 a 20 Sr 38 a) In what way are the electronic arrangements of atoms of magnesium and calcium i) similar to each other? (1 mark) They have the same number of outermost shell electrons. (1) ii) different from each other? (1 mark) They have different number of occupied electron shells. (1) Part b) student added a few pieces of calcium granules into a beaker of cold water. alcium gave a colourless gas with cold water. i) State ONE more observation when calcium reacted with water. (1 mark) alcium sinks in water. / alcium dissolves. (1) ii) The student recorded the following observation in her laboratory report: Evolution of the colourless gas was at first slow but became faster after some time. Suggest an explanation for the student s observation. (2 marks) alcium is covered by a layer of calcium oxide. (1) Reaction between calcium and water starts only when the oxide layer dissolves. (1) c) The electronic arrangement of a strontium (Sr) atom is 2,8,x,8,y. What are the values of x and y? (1 mark) x = 18 (0.5) y = 2 (0.5) 74

75 d) Suggest whether strontium or calcium is more reactive. (1 mark) Strontium is more reactive than calcium. (1) e) Strontium-90 ( 90 Sr) is a radioactive isotope of strontium, and is one of the dangerous by-products of nuclear fission. i) Explain the meaning of the term isotope. (2 marks) Isotopes are different atoms of an element which have the same number of protons (1) but a different number of neutrons. (1) ii) hildren s teeth require a large amount of calcium to grow. Scientists found that in areas where nuclear weapon tests were conducted above the ground, children s teeth contained a higher level of 90 Sr. Suggest a reason for the findings of the scientists. (2 marks) The chemical properties of strontium are similar to those of calcium. (1) Thus strontium can replace some of the calcium required. (1) 94 The following table shows the melting and boiling points of chlorides of some Period 3 elements of the periodic table. Sodium chloride Magnesium chloride Phosphorus trichloride Sulphur dichloride Melting point ( ) oiling point ( ) Part a) raw an electron diagram of magnesium chloride, showing electrons in the outermost shells only. (1 mark) (1) 75

76 b) i) raw an electron diagram of sulphur dichloride, showing electrons in the outermost shells only. (1 mark) (1) ii) Suggest the physical state of sulphur dichloride at room temperature and pressure. (1 mark) Liquid (1) c) Explain the difference in the melting points of the above four chlorides in terms of their structures. (4 marks) Sodium chloride and magnesium chloride have giant ionic structures. (1) To melt them, a lot of heat is needed to overcome the strong ionic bonds between the ions. Hence sodium chloride and magnesium chloride have high melting points. (1) Phosphorus trichloride and sulphur dichloride have simple molecular structures. (1) The attractive forces between the molecules are weak. Little heat is needed to separate the molecules. Hence phosphorus trichloride and sulphur dichloride have low melting points. (1) Part d) iscuss, with explanation, the electrical conductivity of magnesium chloride with reference to the type and property of the particles in it. (3 marks) Magnesium chloride conducts electricity in molten state or aqueous solution but not in solid state. (1) In solid state, the ions in magnesium chloride are held together by strong ionic bonds. They are not free to move. (1) The ions become mobile in molten state or aqueous solution. (1) e) Predict whether sodium chloride is soluble in water. Explain your answer. (3 marks) Sodium chloride is soluble in water. (1) Strong attractive forces exist between ions in sodium chloride and water molecules. (1) These forces cause the ions to move away from the solid and go into the water. (1) 76

77 95 X, Y and Z are three elements in the periodic table, with the sum of their atomic numbers equal to 46. Moreover, both X and Y are Group VII elements, while the atomic number of X is smaller than that of Y. a) What are elements X, Y and Z? (3 marks) X fluorine (1) Y chlorine (1) Z calcium (1) b) Name the group to which Z belongs. (1 mark) lkaline earth metals (1) c) raw an electron diagram of the compound P formed from X and Y, showing electrons in the outermost shells only. (1 mark) (1) d) raw an electron diagram of the compound Q formed from X and Z, showing electrons in the outermost shells only. (1 mark) (1) Part e) ompare the melting points of P and Q. Explain your answer. (3 marks) The melting point of Q is higher than that of P. (1) To melt Q, a lot of heat is needed to overcome the strong ionic bonds between the ions. (1) The attractive forces between the molecules of P are weak. Little heat is needed to separate the molecules. (1) 77

78 F) X combines with nitrogen to form a nitride. raw an electron diagram of the nitride, showing electrons in the outermost shells only. (1 mark) (1) g) Z combines with nitrogen to form a nitride. raw an electron diagram of the nitride, showing electrons in the outermost shells only. (1 mark) (1) Part 96 The following table shows some information about some species. They can be atoms or ions. Species tomic number Mass number Number of protons electrons neutrons E F (0.5 x 12) a) omplete the above table. (6 marks) b) What is the relationship between and? (1 mark) They are isotopes. (1) 78

79 c) What is the relationship between and? (1 mark) is an anion of. (1) d) What is the relationship between E and F? (1 mark) E is a cation of F. (1) e) exists as diatomic molecules. raw an electron diagram of a molecule of, showing electrons in the outermost shells only. (1 mark) (1) f) X is a compound formed from and, while Y is a compound formed from and F. i) raw an electron diagram of X, showing electrons in the outermost shells only. (1 mark) (1) ii) raw an electron diagram of Y, showing electrons in the outermost shells only. (1 mark) Part (1) iii) ompare the melting points of X and Y. Explain your answer. (3 marks) The melting point of Y is higher than that of X. (1) To melt Y, a lot of heat is needed to overcome the strong ionic bonds between the ions. (1) The attractive forces between the molecules of X are weak. Little heat is needed to separate the molecules. (1) 79

80 97 The electron diagram of ammonium chloride is shown below: (Only electrons in the outermost shells are shown.) a) Identify the type of bond which exists between the two ions. (1 mark) Ionic bond (1) b) Identify the type of bond which exists between nitrogen and hydrogen. (1 mark) ovalent bond (1) c) When a hydrogen ion reacts with an ammonia molecule, an ammonium ion is formed. i) Give the name of the type of bond formed when a hydrogen ion reacts with an ammonia molecule. (1 mark) ative covalent bond (1) ii) escribe how this bond is formed in the ammonium ion. (1 mark) The nitrogen atom supplies both bonding electrons to the hydrogen ion. (1) Part d) Explain whether ammonium chloride is soluble in water. (3 marks) mmonium chloride is soluble in water. (1) Strong attractive forces exist between ions in ammonium chloride and water molecules. (1) These forces cause the ions to move away from the solid and go into the water. (1) e) escribe a chemical test to show the presence of chloride ions in a solid sample. State the expected observation(s). (3 marks) issolve the sample in water. (1) Then add excess dilute nitric acid, followed by silver nitrate solution. (1) white precipitate forms. (1) 80

81 98 Explain the following: a) rgon seldom forms compounds with other elements. (2 marks) n atom of argon has 8 electrons in its outermost shell. (1) special stability is obtained when this happens. Hence argon seldom forms compounds with other elements. (1) b) Magnesium and calcium show similar chemical properties. (1 mark) toms of magnesium and calcium have the same number of outermost shell electrons. (1) c) sulphur atom tends to form an ion carrying two negative charges. (1 mark) sulphur atom has an electronic arrangement 2,8,6. It obtains a stable electronic arrangement (2,8,8) by gaining two electrons. (1) d) opper has a high melting point. (2 marks) The ions in copper are packed closely and the metallic bonds holding them together are very strong. (1) To melt a piece of copper, a lot of heat is needed to overcome the strong attractive forces. Hence copper has a high melting point. (1) e) Quartz is a solid which melts at a high temperature while carbon dioxide is a gas at room temperature. (4 marks) Part Quartz has a giant covalent structure. (1) To melt quartz, a lot of heat is needed to overcome the strong covalent bonds between the atoms. Hence quartz has a high melting point. (1) arbon dioxide has a simple molecular structure. (1) The attractive forces between the molecules are weak. Little heat is needed to separate the molecules. Hence carbon dioxide has a low boiling point. (1) 81

82 99 onsider the substances listed below: argon carbon dioxide hydrogen chloride iodine silicon dioxide sodium chloride The following diagram shows the arrangements of particles in three substances X, Y and Z. a) For each case, choose ONE substance from the above list which has arrangement of particles as shown under room temperature and pressure. (3 marks) Substance X sodium chloride (1) Substance Y argon (1) Substance Z iodine (1) b) Name the attractive forces that exist between particles in substance Y. (1 mark) Van der Waals forces (1) c) Predict and explain the following properties of substance X: i) hardness; (2 marks) Part X is hard (1) due to the strong ionic bonds between the ions. Relative motion of the ions is restricted. (1) ii) electrical conductivity in solid and molten states. (3 marks) X does not conduct electricity in solid state but it does in molten state. (1) In solid state, the ions in X are held together by strong ionic bonds. They are not free to move. (1) The ions become mobile in molten state. (1) d) Predict and explain the following properties of substance Z: i) solubility in water; (2 marks) Z is slightly soluble in water. (1) The weak attractive forces between molecules of Z and water are not strong enough to overcome the attractive forces between water molecules. (1) 82

83 ii) solubility in non-aqueous solvents; (2 marks) Z is very soluble in non-aqueous solvents. (1) The attractive forces between molecules of non-aqueous solvents are similar to those between molecules of Z. Hence molecules of Z and non-aqueous solvents mix together easily. (1) iii) electrical conductivity. (2 marks) Z does not conduct electricity (1) becsuse it does not contain mobile electrons or ions. (1) 100 new element X has been recently discovered. It is a solid with a low melting point. It reacts violently with water and catches fire in the reaction. n alkaline solution is formed. a) In which group of the periodic table should X be placed? (1 mark) Group I (1) b) Suggest how X can be stored safely in the laboratory. (1 mark) Store X in paraffin oil. (1) c) X forms a compound with bromine. i) etermine the chemical formula of the compound. (1 mark) Xr (1) ii) o you expect this compound to be volatile? Explain. (3 marks) The compound is not volatile. (1) Part Its ions are held together by strong ionic bonds. (1) lot of heat is needed to overcome the strong ionic bonds. (1) iii) iscuss, with explanation, the electrical conductivity of the compound with reference to the type and property of the particles in it. (3 marks) The compound conducts electricity in molten state or aqueous solution but not in solid state. (1) In solid state, the ions in the compound are held together by strong ionic bonds. They are not free to move. (1) The ions become mobile in molten state or aqueous solution. (1) 83

84 101 The diagrams below show the structures of diamond and graphite. iamond and graphite are allotropes.. a) Explain the meaning of the term allotrope. (2 marks) llotropes are two (or more) forms of the same element (1) in which the atoms or molecules are arranged in different ways. (1) b) o you expect diamond to dissolve in water? Explain your answer. (2 marks) iamond is insoluble in water. (1) This is because the atoms are held together by strong covalent bonds. It is very difficult to separate the atoms. (1) Part c) ased on the structure of diamond, suggest ONE use of it. (1 mark) s a stone cutter (1) d) Explain why diamond is harder than graphite. (2 marks) In graphite, the layers of carbon atoms are held by weak van der Waals forces. The layers can easily slide over each other. Hence graphite is quite soft. (1) In diamond, each carbon atom is bonded to other carbon atoms by strong covalent bonds. Relative motion of the atoms is restricted. Hence diamond is very hard. (1) e) Explain why graphite is used as lubricant. (2 marks) Graphite has a layered structure. Weak van der Waals forces exist between the layers. (1) The layers can easily slide over each other. (1) Hence graphite has a slippery feel. 84

85 f) State a property NOT mentioned above which graphite shares with metals. Explain the cause of this property. (3 marks) Graphite is a good conductor of electricity. (1) Graphite has a layered structure. Within each layer, each carbon atom uses three outermost shell electrons in forming covalent bonds with three other atoms. (1) The remaining electron is delocalized between the layers of carbon atoms. (1) Graphite is a good conductor of electricity due to the presence of delocalized electrons. 102 iamond and graphite are different forms of the same element. The structure of diamond is shown below. a) What type of structure does diamond have? (1 mark) Part Giant covalent structure (1) b) Explain why carbon dioxide is a gas at room temperature and diamond is a solid which melts at a high temperature. (2 marks) The attractive forces between carbon dioxide molecules are weak. Little heat is needed to separate the molecules. Hence carbon dioxide has a low boiling point. (1) iamond consists of a network of covalent bonds. lot of heat is needed to overcome the strong covalent bonds between the atoms. Hence diamond has a high melting point. (1) 85

86 c) Graphite is mixed with clay to make pencil leads. i) Sketch a labelled diagram to show the arrangement of atoms in graphite. (2 marks) (1 mark for the hexagonal arrangement of atoms; 1 mark for labelling the van der Waals forces between the layers of atoms) (2) ii) Suggest why this crystal structure of graphite enables it to leave a mark when a pencil is drawn across a sheet of paper. (2 marks) When graphite is pressed onto a peice of paper, the layers of atoms slide over each other (1) and flake off easily onto the paper. (1) 103 Silicon (Si) and germanium (Ge) have the same crystal structure, as shown below: Part a) What type of structure do silicon and germanium have? (1 mark) Giant covalent structure (1) b) Silicon occurs in nature as silicon dioxide in sand and quartz. raw the three-dimensional structure of silicon dioxide. (2 marks) (1 mark for the correct arrangement of atoms; 1 mark for the correct labelling of silicon and oxygen atoms) (2) 86

87 c) Silicon combines with chlorine to form silicon tetrachloride (Sil 4 ). raw an electron diagram of the chloride, showing electrons in the outermost shells only. (1 mark) (1) d) Explain why silicon dioxide has a higher melting point than silicon tetrachloride in terms of their structures. (2 marks) To melt silicon dioxide, a lot of heat is needed to overcome the strong covalent bonds between the atoms. (1) The attractive forces between silicon tetrachloride molecules are weak. Little heat is needed to separate the molecules. (1) Part e) The table below gives the relative abundance of each isotope in a sample of germanium, Ge. Isotope 70 Ge 72 Ge 74 Ge Relative abundance (%) What is the relative atomic mass of Ge? (2 marks) 70 x x x (1) = 72.4 (1) 87

88 104 t room temperature, both sodium metal and sodium chloride are crystalline solids. a) The diagram below shows part of the lattice of sodium chloride. i) In this diagram, mark all sodium ions with a positive (+) sign and all chloride ions with a negative ( ) sign. (1 mark) (1) ii) What is the number of neighbouring chloride ions directly attached to each sodium ion in crystalline sodium chloride? (1 mark) 6 (1) Part b) i) Explain how the particles are held together in solid sodium metal. (1 mark) The particles in solid sodium metal are held together by a sea of mobile electrons. (1) ii) Explain how the particles are held together in solid sodium chloride. (1 mark) The particles in solid sodium chloride are held together by ionic bonds. (1) iii) The melting point of sodium chloride is much higher than that of sodium metal. What can be deduced from this information? (1 mark) The ionic bonding in sodium chloride is stronger / requires more heat to break than the metallic bonding in sodium. (1) 88

89 c) ompare the electrical conductivity of solid sodium metal with that of solid sodium chloride. Explain your answer. (3 marks) Solid sodium conducts electricity but solid sodium chloride does not. (1) Solid sodium contains mobile electrons (1) but the ions in solid sodium chloride are not free to move. (1) d) Using sodium as an example, describe the bonding in metals. Hence explain why metals are malleable. (2 marks) Ions in sodium are packed in layers. (1) s the metal is struck by a hammer, the ion layers slide through the sea of electrons to new positions. The metal does not break because the ions are still bound together by the sea of electrons. (1) s a result, sodium is malleable. 105 The symbols p, q, r, s, t, u, v and w represent eight consecutive elements in the second and third periods of the periodic table. The table below lists their boiling points: Element p q r s t u v w oiling point ( ) nswer: e N O F Ne Na Part a) educe from the above information which elements r and s represent respectively. (3 marks) Element r has the highest boiling point and (1) a sudden drop in boiling point occurs from r to s. (1) Hence r is carbon while s is nitrogen. (1) b) Explain why element t has a low boiling point. (2 marks) The attractive forces between the molecules of t are weak. (1) Little heat is needed to separate the molecules. (1) c) Indentify ONE metalloid in the above table. (1 mark) q (1) 89

90 d) State, with explanation, which of the elements is stored in paraffin oil. (2 marks) Element w is stored in paraffin oil (1) as it is very reactive. (1) e) Suggest ONE use of element v. (1 mark) In advertising signs (1) f) X is a compound formed from elements t and u. raw an electron diagram of X, showing electrons in the outermost shells only. (1 mark) (1) g) Y is a compound formed from elements t and w. raw an electron diagram of Y, showing electrons in the outermost shells only. (1 mark) Part (1) h) ompare the melting points of X and Y. Explain your answer. (3 marks) The melting point of Y is higher than that of X. (1) To melt Y, a lot of heat is needed to overcome the strong ionic bonds between the ions. (1) The attractive forces between the molecules of X are weak. Little heat is needed to separate the molecules. (1) 90

91 106 The diagram below shows the relative electrical conductivities of the first three elements in Period 3. a) escribe the bonding in magnesium. Hence explain why magnesium is a good conductor of electricity. (3 marks) The outermost shell electrons of each magnesium atom are free to move randomly in magnesium. (1) Thus, magnesium consists of positively charged ions surrounded by a sea of electrons. (1) Magnesium is a good conductor of electricity due to the movement of mobile electrons in the metal. (1) b) Explain why the electrical conductivity of aluminium is higher than that of magnesium. (2 marks) Part Each aluminium atom has three outermost shell electrons while a magnesium atom has two. (1) There are more delocalized electrons in aluminium. (1) So, the electrical conductivity of aluminium is higher. c) Explain why metals are ductile. (2 marks) Ions in a metal are packed in layers. (1) s the metal is struck by a hammer, the ion layers slide through the sea of electrons to new positions. The metal does not break because the ions are still bound together by the sea of electrons. (1) s a result, the metal is ductile. 91

92 d) Explain whether molten sulphur can conduct electricity. (2 marks) Molten sulphur cannot conduct electricity (1) because it does not contain mobile electrons or ions. (1) 107 Read the passage below and answer the questions that follow. evelopment of the periodic table In 1869, Mendeléev arranged the elements in the form of the periodic table. efore this many other scientists tried to make sense of all the information about the elements. The table below is part of the table of elements devised by the English chemist John Newlands in He arranged the elements in order of their relative atomic masses. He found a repeating pattern, with elements having similar properties in the vertical columns (Groups). H Li e N O F Na Mg l Si P S l K a r Ti Mn Fe o / Ni u Zn Y In s Se r Rb Sr e / La Zr i / Mo Ro / Ru Part Many scientists were critical of the pattern suggested by Newlands. The diagram below shows a version of Mendeléev s Periodic Table. Mendeléev placed most of the elements in order of relative atomic mass. This table became accepted by other scientists. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 Group 8 Period 1 H Period 2 Li e N O F Period 3 Na Zn l Si P S l Period 4 K u a Zn?? Ti? V s r Se Mn r Fe o Ni Period 5 Rb g Sr d Y In Zr Sn Nb Sb Mo Te? I Ru Rh Pd 92

93 a) i) Which group of elements, present in the modern periodic table, is missing from Newlands table above? (1 mark) Group 0 (1) ii) Explain why this group was missing from Newlands classification of elements. (1 mark) Not yet discovered at that time (1) b) Newlands put hydrogen, fluorine and chlorine in the same group. Give ONE property of hydrogen which makes it similar to fluorine and chlorine. (1 mark) Exists as diatomic molecules / exists as a gas at room conditions / any other general property of non-metals (1) c) Suggest why other scientists were critical of Newlands table. You should give examples from the table and use your knowledge of the chemistry of the elements. (4 marks) ny two of the following: Many elements in the groups have very dissimilar properties, e.g. K and u. (2) Two elements were put in one place, e.g. e and La. (2) Metals and non-metals were mixed up, e.g. l and o in the same group. (2) d) Give TWO ways in which Mendeléev s table improved on Newlands table. (2 marks) ny two of the following: Elements with similar properties were grouped together. (1) Part Gaps left for elements to be added when discovered. (1) new group created / iron, cobalt and nickel put in a group. (1) Metals and non-metals were separated. (1) e) Suggest how elements are arranged in a modern periodic table. (1 mark) In order of increasing atomic number (1) 93

94 108 Read the passage below and answer the questions that follow. new form of carbon The carbon allotropes, diamond and graphite, have been known for centuries. In 1985, a new form of carbon buckminsterfullerene was discovered. This new form of carbon contains 60 molecules. Each 60 molecule is formed by 60 carbon atoms bonded together like a football as shown in the diagram below: The new form of carbon is virtually insoluble in water, but soluble in non-aqueous solvents, such as toluene. Interest in buckminsterfullerene has led to the discovery of a related group of carbon structures referred to as nanotubes. Nanotubes may be viewed as rolled up segments of graphite. Part arbon nanotubes have a high strength. arbon nanotube-based materials are being widely researched to develop ultra lightweight and extremely strong materials. a) What is meant by the term allotropes? (2 marks) llotropes are two (or more) forms of the same element (1) in which the atoms or molecules are arranged in different ways. (1) b) What type of structure does buckminsterfullerene have? Expain your answer. (3 marks) uckminsterfullerene has a simple molecular structure. (1) uckminsterfullerene is soluble in non-aqueous solvents. (1) It can be deduced that the attractive forces between molecules of buckminsterfullerene are similar to those between molecules of non-aqueous solvents. (1) 94 Hence it can be concluded that buckminsterfullerene has a simple molecular structure.

95 c) How would you expect the melting point of buckminsterfullerene to compare with that of diamond? Explain your answer. (3 marks) The melting point of diamond is higher than that of buckminsterfullerene. (1) iamond has a giant covalent structure. The carbon atoms are held together by strong covalent bonds. (1) There are weak van der Waals forces between the buckminsterfullerene molecules. (1) More heat is needed to break the strong covalent bonds between atoms in diamond. Hence diamond has a higher melting point. d) Explain the high strength of carbon nanotubes with reference to the bonding in them. (1 mark) The carbon atoms are held together by strong covalent bonds. (1) e) Graphite is used to make electrodes in dry cells. It is also used to make strong but lightweight fishing rods. i) Explain why graphite can conduct electricity with reference to its structure. (3 marks) In graphite, the carbon atoms are arranged in flat parallel layers. (1) Within each layer, each carbon atom uses three electrons in forming covalent bonds with three other carbon atoms. (1) The remaining outermost shell electron of each carbon atom is delocalized between the layers of carbon atoms. (1) Part ii) Explain why graphite can bend so that it is suitable for making a fishing rod. (2 marks) Graphite has a layered structure. Weak van der Waals forces exist between the layers. (1) The layers of atoms can slide over each other easily. (1) f) Suggest and explain how you would distinguish between buckminsterfullerene and graphite by a physcial method. (3 marks) dding a non-aqueous solvent to each solid separately, buckminsterfullerene is soluble while graphite is insoluble. (1) uckminsterfullerene has a simple molecular structure and is soluble in non-aqueous solvents. (1) Graphite has a giant covalent structure. It is insoluble in most solvents. (1) 95

96 109 Read the passage below and answer the questions that follow. hemistry of fireworks erial shells are the most common types of fireworks for public displays. shell consists of a paper tube filled with stars and a black powder. Stars are small lumps consisting of an oxidizing agent, a reducing agent and metal salts. The black powder is a mixture of carbon powder, sulphur powder and potassium nitrate powder. Located just below the shell is a lift charge containing the black powder as well. Upon ignition, the potassium nitrate, sulphur and carbon (in the black powder) in the lift charge react to form carbon dioxide and nitrogen gases, and potassium sulphide. potassium nitrate + carbon + sulphur potassium sulphide + carbon dioxide + nitrogen The shell is sent up into the air. t the precise altitude, the black powder inside the shell is ignited, causing the shell to explode. The explosion also ignites the stars, scattering them in all directions across the sky. The colours of fireworks are produced by burning metal salts. For example, a red colour can be produced by using strontium nitrate while a green colour produced by using barium nitrate. a) Explain the meaning of the term mixture. (2 marks) mixture consists of two or more pure substances (1) which have not been chemically joined together. (1) Part b) raw an electron diagram of a nitrate ion, showing electrons in the outermost shells only. (1 mark) (1) c) Explain how the lift charge sends the shell into the air. (2 marks) The pressure from the expanding gases propels the shell into the air (2) d) i) What solid residue is left behind when the black powder explodes? (1 mark) Potassium sulphide (1) ii) Wht is the chemical formula of the solid suggested in (i)? (1 mark) K 2 S (1) 96