In a similar way, draw the electronic structure for magnesium. (3)

Similar documents
Q1. The periodic table on the Data Sheet may help you to answer this question.

Give the number of protons, neutrons and electrons in this atom of aluminium. Why is aluminium positioned in Group 3 of the periodic table? ...

Mendeleev arranged the elements in order of their atomic mass (atomic weight).

Name: Periodic Table. Class: Foundation revision questions. Date: 39 minutes. Time: 39 marks. Marks: Comments: Page 1 of 12

Q1.Use the periodic table and the information in the table below to help you to answer the questions.

Q1. The diagram shows some of the elements in Groups I and 7 of the Periodic Table. The elements in Group 1 have similar chemical properties.

Page 2. Q1.The electronic structure of the atoms of five elements are shown in the figure below. The letters are not the symbols of the elements.

Year 8 Chemistry Knowledge Organiser Topic 1: Periodic Table

Half Yearly Exam 2015

1 Arranging the Elements

GOZO COLLEGE BOYS SECONDARY SCHOOL

The Periodic Table Question Paper 3

Chemistry Summer Holiday Homework Year Y9 & 10

4.1 Atomic structure and the periodic table. GCSE Chemistry

Chapter 2 Atoms and the Periodic Table

About 3000 million years ago carbon dioxide was one of the main gases in the Earth s early atmosphere.

Using the Periodic Table

M1. (a) (i) argon and potassium or tellurium and iodine or cobalt and nickel accept correct symbols allow argon and calcium 1

AQA (Trilogy) Combined Science GCSE Unit 5.1 Atomic Structure and the Periodic Table

Full file at

6.3 Classifying Elements with the Periodic Table

Page 1 of 9. Website: Mobile:

1 Arranging the Elements

...[1] (ii) Name two elements from group 0....[2] (b)(i) Which box best represents particles from group 0 elements?...[1]......[1]

Calculate the mass of iron that could be extracted from 1000 kg of iron oxide. Use your answer to part (c) (ii) to help you with this calculation.

Q1. Methane and oxygen react together to produce carbon dioxide and water.

Periodic Table Workbook

Reporting Category 1: Matter and Energy

Unit 3 Atomic Structure

Half Yearly Exam 2015

Particles and Periodic Table

Atomic Structure and the Periodic Table. AQA Chemistry topic 1

In this activity, you will use the same information they had to construct your own periodic table.

Searching for an Organizing Principle. Searching for an Organizing Principle. How did chemists begin to organize the known elements?

Reporting Category 1: Matter and Energy

Principles of Chemistry: A Molecular Approach 2e (Tro) Chapter 2 Atoms and Elements

Why all the repeating Why all the repeating Why all the repeating Why all the repeating

16+ ENTRANCE EXAMINATION

1 Electrons and Chemical Bonding

Honors Chemistry - Unit 4 Bonding Part I

Electrochemistry. Part One: Introduction to Electrolysis and the Electrolysis of Molten Salts

1. The arrangement of the elements from left to right in Period 4 on the Periodic Table is based on

Unit 3. Atoms and molecules

Advanced Chemistry. Mrs. Klingaman. Chapter 5: Name:

CHEMICAL COMPOUNDS MOLECULAR COMPOUNDS

Part A Unit-based exercise

Q1. The electronic structure of the atoms of five elements are shown in the figure below.

Principles of Chemistry: A Molecular Approach, 3e (Tro) Chapter 2 Atoms and Elements

HSVD Ms. Chang Page 1

Chemical Families. Group 0 The Noble Gases

CH3FP. (Jun15CH3FP01) General Certificate of Secondary Education Foundation Tier June Unit Chemistry C3 PMT. Time allowed 1 hour TOTAL

Writing Chemical formula with polyatomic groups

SNC1D CHEMISTRY 2/8/2013. ATOMS, ELEMENTS, & COMPOUNDS L The Periodic Table (P ) The Early Periodic Table. The Early Periodic Table

Honors Chemistry Unit 4 ( )

Test 3: Lab Safety, Measurements, Matter and Periodic Table

Chemistry: A Molecular Approach, 2e (Tro) Chapter 2 Atoms and Elements. Multiple Choice Questions

Atoms and Ions Junior Science

100% ionic compounds do not exist but predominantly ionic compounds are formed when metals combine with non-metals.

Note Taking Guide: Episode 401. arranged elements by. predicted of missing. discovered that each has a unique. arranged elements by

Developing the Periodic Table

Periodic Table of the Chemical Elements

Chapter 3: Elements and Compounds. 3.1 Elements

Name: SCH3U Worksheet-Trends

Further Additional Science

Ch. 3 Answer Key. O can be broken down to form two atoms of H and 1 atom of O. Hydrogen and oxygen are elements.

ICSE Board Class IX Chemistry Paper 5 Solution

Elements and the Periodic Table

1. The elements on the Periodic Table are arranged in order of increasing A atomic mass C molar mass

1. The elements on the Periodic Table are arranged in order of increasing A atomic mass C molar mass

CHEMICAL COMPOUNDS MOLECULAR COMPOUNDS

materials and their properties

CHEMICAL COMPOUNDS. - Dalton's theory does not mention this, but there is more than one way for atoms to come together to make chemical compounds!

History of the Periodic Table

Unit 1 Part 2 Atomic Structure and The Periodic Table Introduction to the Periodic Table UNIT 1 ATOMIC STRUCTURE AND THE PERIODIC TABLE

VIIIA He IIA IIIA IVA VA VIA VIIA. Li Be B C N O F Ne. Na Mg VIB VIIB VIIIB IB IIB S. K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br

Periodic Table Practice 11/29

Atomic structure. The subatomic particles. - a small, but relatively massive particle that carres an overall unit POSITIVE CHARGE

The Periodic Table. LESSON 10 Breaking the Code. Think About It. Exploring the Topic. The Modern Periodic Table

(a) (i) What is represented by... (ii) What is represented by... (2) (b) What is the symbol for lithium?... (1) (Total 3 marks)

Fundamentals of General, Organic & Biological Chemistry 4 th Edition. Matter and Life

CHEMICAL COMPOUNDS MOLECULAR COMPOUNDS

X Chemistry: Periodic Classification of elements. Gist of Lesson for Quick Revision (By JSUNIL)

Organizing the Periodic Table

Periodic Table. - Mendeleev was able to predict the properties of previously unknown elements using his "periodic law" Modern periodic table

Periodic Table. Modern periodic table

Atomic terms. Example: Helium has an atomic number of 2. Every helium atom has two protons in its nucleus.

Honors Chemistry: Chapter 4- Problem Set (with some 6)

Orchard School. New Document 1 Name: Class: Date: 129 minutes. Time: 126 marks. Marks: Comments: Page 1

- Some properties of elements can be related to their positions on the periodic table.

IONIC COMPOUNDS. - USUALLY form from metals combining with nonmetals, or from metals combining with metalloids

Secondary Support Pack. be introduced to some of the different elements within the periodic table;

Part I Assignment: Electron Configurations and the Periodic Table

Essential Chemistry for Biology

Periodic Table. Modern periodic table

Unit 4 - Periodic Table Exam Name: PRACTICE QUESTIONS Date: 2/23/2016

Atomic weight: This is a decimal number, but for radioactive elements it is replaced with a number in parenthesis.

Name: Chemistry Unit Review Science 9

NUCLEAR MODEL. Electron cloud. Electron cloud. Nucleus. Nucleus

CHEMICAL COMPOUNDS MOLECULAR COMPOUNDS

M11/4/CHEMI/SPM/ENG/TZ2/XX CHEMISTRY STANDARD LEVEL PAPER 1. Monday 9 May 2011 (afternoon) 45 minutes INSTRUCTIONS TO CANDIDATES

Transcription:

Q1. Three elements in Group 2 of the periodic table are beryllium (Be), magnesium (Mg) and calcium (Ca). Their mass numbers and proton numbers are shown below. The electronic structure is shown for beryllium and calcium. (a) In a similar way, draw the electronic structure for magnesium. (3) (b) The three elements have similar chemical properties The reactivity of these elements with non-metals, increases from beryllium to magnesium to calcium. Explain these two statements in terms of atomic structure................... (6) (Total 9 marks) Q2. Part of the Periodic Table is shown below. Use the information to help you answer the questions which follow. Page 1 of 30

(a) Write the symbol for: chlorine;... sodium.... (b) What is the symbol of the element which is in Group 2 and Period 3?... What name is given to Group 7?.. (c) The arrangement of electrons in sulphur (S) is 2.8.6. Write the arrangement of electrons for: neon (Ne);... aluminium (Al).... (d) The Periodic Table is an arrangement of elements in order of increasing atomic number. What is the atomic number of an element?... (e) What is the name of the uncharged particle in the nucleus of an atom?... (Total 8 marks) Page 2 of 30

Q3. Complete the table which shows some of the physical properties of bromine, chlorine and iodine. Melting point in C Boiling point in C Physical state at 23 C Colour of vapour Bromine 7 58.... Chlorine 101 34.. greenish Iodine 114 183.... (Total 2 marks) Q4. Use the periodic table on the Data Sheet to answer these questions. The table below gives the electronic structures of four elements, W, X, Y and Z. Element Electronic structure W 2,5 X 2,7 Y 2,8,8 Z 2,8,8,1 (a) Which element W, X, Y or Z: is a Group 0 gas?... is nitrogen?... (iii) is a Group 7 gas?... (iv) reacts violently with water?... (3) (b) Which two Groups of the periodic table do not contain any non-metals?... (Total 4 marks) Page 3 of 30

Q5. Part of the Periodic Table which Mendeleev published in 1869 is shown below. Use the Data Sheet to help you to answer this question. (a) Name two elements in Group 1 of Mendeleev s Periodic Table which are not found in Group 1 of the modern Periodic Table.... and... (b) Which group of elements in the modern Periodic Table is missing on Mendeleev s table?... (c) Mendeleev left several gaps in his Periodic Table. These gaps are shown as asterisks(*) on the table above. Suggest why Mendeleev left these gaps.......... (d) Complete the following sentence. In the modern Periodic Table the elements are arranged in the order of their... numbers. (Total 5 marks) Page 4 of 30

Q6. Part of the Periodic Table which Mendeleev published in 1869 is shown below. Use the Data Sheet to help you to answer this question. (a) Give the symbols of two elements in Group 1 of Mendeleev s Periodic Table which are not found in Group 1 of the modern Periodic Table.... and... Name these two elements.... and... (b) Which group of elements in the modern Periodic Table is missing on Mendeleev s table?... (c) Mendeleev left several gaps in his Periodic Table. These gaps are shown as asterisks(*) on the table above. Suggest why Mendeleev left these gaps.......... (d) Complete the following sentence. In the modern Periodic Table the elements are arranged in the order of their... numbers. Page 5 of 30

(e) Mendeleev placed lithium, sodium and potassium in Group 1 of his Periodic Table. This was because they have similar properties. Some properties of elements are given in the table. Four of them are properties of lithium, sodium and potassium. One of these properties has been ticked for you. Place a tick next to the other three properties. PROPERTY They react with water to give alkaline solutions. They are gases. They are non-metals. They form an ion with a 1+ charge. They react with water and give off hydrogen. They form an ion with a 1 charge. They are metals. They react with water to give acidic solutions. (3) (f) What happens when a small piece of sodium reacts with water? You should describe what you would see and state what substances are formed................... (3) (Total 12 marks) Q7. Read the following information about an element X. The element X melts above 600 C. It conducts electricity at room temperature. It burns in oxygen to form an oxide. When the oxide is mixed with water it turns Universal Indicator blue. The oxide of X is a white solid at room temperature. It has the formula XO and contains the ion X 2+. The element X reacts with chlorine to form a chloride with a high melting point. The chloride conducts electricity when molten and it is soluble in water. Page 6 of 30

(a) From the information give three pieces of evidence which suggest that X is a metal. 1...... 2...... 3...... (3) (b) In which Group of the Periodic Table should X be placed? Give a reason for your answer. Group. Reason...... (c) Predict the formula for the chloride of X.... (Total 6 marks) Q8. HYDROGEN FUEL OF THE FUTURE It has been suggested that hydrogen could be used as a fuel instead of the fossil fuels that are used at present. The equation below shows how hydrogen burns in air. 2H 2 + O 2 2H 2 O + heat The hydrogen would be made from water using energy obtained from renewable sources such as wind or solar power. The water splitting reaction requires a lot of energy. (a) Hydrogen was successfully used as a fuel for a Soviet airliner in 1988. Why would hydrogen be a good fuel for use in an aeroplane?............ Page 7 of 30

(b) The water splitting reaction is shown in the equation below. 2H 2 O 2H 2 + O 2 Calculate the energy needed to split the water molecules in the equation into H and O atoms. 2H 2 O 4H + 2O...... (c) On the Periodic Table, hydrogen is placed on its own at the top and in the middle. It is difficult to position it because it has the properties of metals and non-metals. Where would you expect hydrogen to be placed on the periodic table on the basis of the arrangement of electrons in hydrogen atoms?...... Explain your answer....... Give one way in which hydrogen behaves like a metal....... (iii) Give one way in which hydrogen behaves like a non-metal....... (Total 8 marks) Page 8 of 30

Q9. The Periodic Table contains groups of elements that have similar chemical properties. (a) The halogens are in Group 7 of the Periodic Table. Complete the table. Iodine has been done for you. Halogen Colour of vapour chlorine iodine red-brown purple Why do the halogens have similar chemical properties?...... (b) The alkali metals are in Group 1 of the Periodic Table. State what is formed when any alkali metal reacts with water................ (Total 5 marks) Q10. The electron arrangements of calcium and magnesium atoms are shown. Page 9 of 30

(a) Which group of the Periodic Table contains calcium and magnesium? Give a reason for your answer....... (b) Small pieces of calcium in cold water move up and down as in the diagram. Suggest why the calcium does this..... Predict what happens when magnesium is added to cold water..... (c) Magnesium burns in air to form a white solid. When water is added to the solid a cloudy alkaline solution of magnesium hydroxide is formed. Name the white solid... Suggest the ph of the magnesium hydroxide solution... (iii) Why is the solution cloudy?.. Page 10 of 30

(iv) Complete the balanced chemical equation for the formation of the magnesium hydroxide from the white solid.... + H 2 O... (Total 9 marks) Q11. This question is about the Periodic Table. (a) Dimitri Mendeleev was a Russian scientist who, in 1869, helped to develop the Periodic Table. He made his table with the known elements arranged in order of increasing atomic mass. He started new rows so that elements with similar chemical properties would be in the same column. Mendeleev sometimes had to leave gaps in his table. Complete the sentences. The Periodic Table is now the arrangement of the elements in order of increasing atomic.... The rows are called... and the columns are called.... (3) Suggest why Mendeleev had to leave gaps in his table....... (b) This section of the Periodic Table shows the positions of some elements. Give the chemical symbol for one of the noble gases.... Page 11 of 30

Draw the arrangement of electrons around the nucleus for the noble gas that you chose in. (iii) Why do the electron arrangements of lithium, sodium and potassium make them react in a similar way?...... (iv) Small pieces of lithium, potassium and sodium are added to water. What is the order of reactivity for these three metals? Put the most reactive metal first....... (v) Complete and balance the chemical equation for the reaction of sodium with water. 2Na(s) + 2H 2 O(l)...NaOH(aq) +...(g) (Total 10 marks) Page 12 of 30

Q12. Lithium is a very reactive metal. (a) Lithium reacts with cold water. Which physical property of lithium is seen during this reaction?.. Which chemical property of lithium will be shown by the universal indicator?.. (b) Complete the sentence by writing in the missing numbers. Lithium has an atomic number of 3 and a mass number of 7. This means that an atom of lithium has... protons... electrons and... neutrons. (3) (Total 5 marks) Q13. Mendeleev constructed a periodic table in 1869. In his periodic table: most of the elements were put in order of increasing relative atomic mass; elements with similar properties were put into groups; Mendeleev changed the order of some elements to put them with similar elements; spaces were left for elements that Mendeleev thought would be discovered in the future. Page 13 of 30

One space was in Group 3 between the elements aluminium and indium. Group 3 Boron Aluminium? Indium Thallium Mendeleev called this undiscovered element eka-aluminium. This element is now known as gallium. In 1871, he also predicted some of the properties of gallium. The table shows the properties of aluminium and indium, along with some of the predictions made by Mendeleev for gallium. Appearance Metal or non-metal Boiling point in C Density in g per cm3 Relative atomic mass Aluminium silvery white metal 2467 2.7 27 Predicted properties of gallium silvery white metal?? 68 Indium silvery white metal 2080 7.31 115 Suggest two reasons why other scientists in 1871 did not accept Mendeleev s periodic table. Reason 1...... Reason 2...... Suggest why the discovery of gallium in 1875 convinced other scientists that Mendeleev s table was correct.......... (Total 3 marks) Page 14 of 30

Q14. The periodic table on the Data Sheet may help you to answer this question. (a) Newlands and Mendeleev both designed periodic tables in which the elements were put in the order of their relative atomic masses. When the elements are put in this order a few of them are placed incorrectly when compared with a modern periodic table. Give one example of a pair of elements that would be placed incorrectly if they were in the order of their relative atomic masses.... and... Explain why placing these two elements in the order of their relative atomic masses would not be correct....... (b) In the modern periodic table the elements are put in order of their atomic (proton) numbers. Explain how the positions of the elements in the periodic table are linked to the electronic structure of their atoms............. (Total 4 marks) Q15. Chlorine and bromine are important Group 7 elements. (a) Explain why chlorine is added to drinking water....... (b) Describe what you would see when bromine water is added to an unsaturated organic compound....... Page 15 of 30

(c) Bromine can be extracted from seawater. The dissolved bromide ions are reacted with chlorine. Bromine and chloride ions are formed. Complete and balance the equation below, which represents the reaction between chlorine and bromide ions. Cl 2 + 2Br... +... Describe what you see when chlorine is added to a solution containing bromide ions....... (d) In terms of electronic structure: state why bromine and chlorine are both in Group 7...... explain why bromine is less reactive than chlorine...................... (3) (e) What is the result of adding acidified silver nitrate solution to a solution containing: chloride ions... bromide ions?... (Total 10 marks) Page 16 of 30

...Na +...H 2 O... + H 2 Q16. Sodium is a Group 1 element. (a) A small piece of sodium is added to some water containing Universal Indicator solution. Describe what you would see happening. (3) Complete and balance the equation for the reaction of sodium with water. (b) Francium is the most reactive element in Group 1. Explain why in terms of electronic structure. (3) (c) The transition elements have different properties from the elements in Group 1. Give two of these different properties of transition elements. 1... 2... (Total 10 marks) Page 17 of 30

Q17. Use the periodic table on the Data Sheet and the information below to help you answer these questions. Mendeleev was one of the first chemists who classified elements in a systematic way based on atomic weight. He suggested his version of the periodic table in 1869. He put the elements in order of their atomic weights but reversed the order for some pairs of elements. Then he arranged them in a table so that chemically similar elements were in columns known as Groups. He also left gaps and made predictions. Part of Mendeleev s table is shown below. Group 1 Group 2 Group 3 Group 4 Group 5 Group 6 Group 7 H Li Be B C N O F Na Mg Al Si P S Cl K Ca # Ti V Cr Mn Cu Zn # # As Se Br Rb Sr Y Zr Nb Mo # Ag Cd In Sn Sb Te I The gaps Mendeleev left are shown by #. By unknown / неизвестен (here / здесь) [Public domain], via Wikimedia Commons Page 18 of 30

3 (a) Which group of elements in the modern periodic table is missing from Mendeleev s table? (b) Mendeleev reversed the order for some pairs of elements. For example, he put tellurium (Te, atomic weight 128) before iodine (I, atomic weight 127), as shown in his table. Why did he do this? (c) In 1869 many chemists did not agree with Mendeleev s periodic table. Suggest three reasons why. (3) (d) In the 20th century, the arrangement of elements in the periodic table was explained in terms of atomic structure. Describe the links between atomic structure and the periodic table. (Total 7 marks) Page 19 of 30

Q18. Read the information about protecting the bottoms of ships. A Copper-bottomed Investment From the 16th to the 19th century, the bottoms of many wooden ships were protected from marine organisms by being covered with sheets of metal. At first lead was used on the bottoms of ships, then copper was used until 1832 when Muntz Metal replaced it. Muntz Metal is an alloy of two transition metals, copper and zinc. Table of data Lead Copper Muntz Metal Cost ( /kg) 1.20 3.20 2.30 Melting point ( C) 327 1083 904 Stops sea worms attacking wood Yes Yes Yes Stops barnacles and seaweed sticking to the bottom of the ship No Yes Yes (a) Use the information to answer the following questions. Suggest why copper replaced lead. Page 20 of 30

Suggest why Muntz Metal replaced copper. (b) A sample of Muntz Metal contains a very small amount of iron as an impurity. Name an instrumental method of analysis that could be used to detect iron. Suggest why an instrumental method would detect the iron in this sample of Muntz Metal but a chemical method is not likely to be successful. (c) Today, ships are made from steel. Steels are alloys of iron, a transition metal. Give two properties of transition metals that make them suitable for making ships. Property 1... Property 2... (Total 6 marks) Page 21 of 30

Q19. The periodic table on the Data Sheet may help you answer these questions. (a) Many chemists have contributed to the development of the periodic table. John Newlands was one of the first chemists who attempted to classify elements in a systematic way based on atomic weight. In 1866 he suggested that there was a repeating pattern of elements with similar properties every eighth element. Part of Newlands periodic table is shown below. H Li Be B C N O F Na Mg Al Si P S Cl K Ca Cr Ti Mn Fe Co, Ni Cu Zn Y In As Se Br Rb Sr Ce, La Zr Di, Mo Ro, Ru Many chemists in 1866 did not accept Newland&#x2019s; periodic table. By Conget at nl.wikipedia [Public domain], from Wikimedia Commons Give one piece of evidence which supports Newlands ideas. Page 22 of 30

Suggest two reasons why many chemists in 1866 did not accept Newlands ideas. 1... 2... (b) Chlorine, bromine and iodine are Group 7 elements. A student investigated the reactivity of these elements. The student added: aqueous chlorine to potassium bromide and potassium iodide solutions aqueous bromine to potassium chloride and potassium iodide solutions aqueous iodine to potassium chloride and potassium bromide solutions. The student s results are shown below. Solution Potassium chloride Potassium bromide Potassium iodide Chlorine Solution turned orange-brown Solution turned brown Bromine No reaction Solution turned brown Iodine No reaction No reaction Use these results to state and explain the trend in reactivity of these Group 7 elements. Page 23 of 30

Complete the equation below, which represents the reaction between chlorine and potassium bromide. Cl 2 + 2KBr... + 2KCl (iii) In terms of electronic structure, state why chlorine, bromine and iodine are in Group 7. (c) Lithium, sodium and potassium are Group 1 elements. Group 1 elements become more reactive down the group. Explain why in terms of electronic structure. (3) (Total 10 marks) Page 24 of 30

Q20. Platinum and gold are transition elements. They can both be used to make wedding rings. By Jeff Belmonte from Cuiabá, Brazil (Flickr) [CC-BY-2.0], via Wikimedia Commons (a) Platinum and gold are good materials for making wedding rings. Use your knowledge of the properties of transition elements to suggest why. (b) Explain, in terms of electronic structure, why transition elements have similar chemical properties. (Total 4 marks) Page 25 of 30

Q21. John Newlands was a chemist who worked in a sugar factory. In 1866 he designed a periodic table. He arranged the elements in order of their relative atomic masses. He found a repeating pattern for some of the elements. Newlands wrote, the eighth element starting from a given one, is a kind of repetition of the first, like the eighth note in an octave of music. H Li G Bo C N O F Na Mg Al Si P S Cl K Ca Cr Ti Mn Fe Co, Ni Cu Zn Y In As Se Br Rb Sr Ce, La Zr Di, Mo Ro, Ru Pd Ag Cd U Sn Sb Te I Cs Ba, V Ta W Nb Au Pt, Ir Tl Pb Th Hg Bi Os Newlands periodic table (a) In Newlands periodic table, the elements lithium, sodium and potassium are grouped together. Give two properties of these elements which support the idea that they should be grouped together. 1... 2... Page 26 of 30

(b) Newlands periodic table was not accepted by most chemists in 1866. Suggest reasons why. Use the Newlands periodic table above to help you to answer this question. (3) (c) State and explain one way in which Mendeleev improved Newlands periodic table. (Total 7 marks) Q22. Lithium is in Group 1 of the periodic table. Lithium reacts with water to produce a gas and an alkaline solution. (a) Name the gas produced. Which ion causes the solution to be alkaline? Page 27 of 30

(b) Potassium is also in Group 1 of the periodic table. Potassium reacts with water in a similar way to lithium. Write down two differences you would see between the reactions of potassium and lithium with water. 1... 2... (Total 4 marks) Q23. The graph shows the boiling points of the halogens. (a) Use the graph to help you answer these questions. Use the correct answer from the box to complete the sentence. gas liquid solid At room temperature chlorine is a.... Describe the trend in boiling point from fluorine to iodine. (b) Chlorine reacts with metals to produce metal chlorides. When a chlorine atom forms a chloride ion it gains one electron. What is the charge on a chloride ion? Page 28 of 30

Write a word equation for the reaction between sodium and chlorine. (c) In the UK water companies add chlorine to tap water. Why is chlorine added to tap water? (d) Water companies add fluoride to tap water in some parts of the UK. Fluoride is added to improve dental health. Suggest one reason why some people are against adding fluoride to tap water. (Total 6 marks) Page 29 of 30

Page 30 of 30