Unit 7 Study Guide: Name: KEY Atomic Concepts & Periodic Table Focus Questions for the unit... How has the modern view of the atom changed over time? How does a chemist use symbols and notation to communicate facts about atoms of elements? How and why do chemical properties of the elements vary in a cyclical pattern (what trends are there and why do they exist)? Vocabulary: Topic 1: REVIEW Atomic Structure gold foil experiment cathode ray tube (CRT) atom o subatomic particle(s) proton electron neutron atomic structure o nucleus o electrons energy levels, orbitals and electron clouds (wavemechanical model) atomic number nuclear charge valence electrons o Lewis dot diagrams o Bohr diagrams o electron configuration elements o metals o nonmetals o metalloids (semi-metals) o noble gases periodic law o periods o groups alkali metals alkaline earth metals transition metals noble gases halogens Topic 2: Ground State vs. Excited State ground state excited state o energy absorbed bright line spectrum o energy released (emission) Topic 3: Calculating Weighted Atomic Mass atomic mass o weighted atomic mass o isotopes (naturally-occurring) atomic mass unit Topic 4: Property Trends in Groups & Periods properties o ionization energy o electronegativity o reactivity o luster o ductility o malleability o conductivity o brittleness & hardness Topic 5: Structure Determines Properties Allotropes
Unit 7 Vocabulary Practice: Alkali Metal Electron Alkaline Earth Metal Electronegativity Allotropes Excited State Atomic Mass Ground State Atomic Number Halogen Bohr Ion Bright-Line Spectrum Ionization Energy Isotope Mass Number Metalloid Neutron Noble Gas Proton Reactivity Rutherford Thomson Valence Electrons Wave-Mechanical Model Alkaline Earth Metal 1. An element of Group 2. Mass Number Electronegativity Atomic Number Isotope Bohr Allotropes Metalloid Atomic Mass Electron 2. The total number of protons and neutrons in the nucleus of an atom. 3. A scale ranking the desire for electrons, with nonmetals having the highest values. 4. The number of protons in the nucleus of an atom. 5. Atom of an element that has a specific number of protons and neutrons. 6. Scientist who discovered that electrons must reside in fixed energy levels around the nucleus. 7. A different structural form of the same element, resulting in different properties. 8. An element that has both metallic and nonmetallic properties. 9. The weighted average mass of all naturally-occurring isotopes in a sample of an element. 10. These negatively-charged subatomic particles can be found in a cloud surrounding the positive nucleus of an atom. Ground State 11. The state of an atom when electrons fill the lowest energy levels. Alkali Metal 12. An element of Group 1. Noble Gas 13. A non-reactive element that can be found in Group 18 on the periodic table. Ion 14. An atom that has either lost or gained electron(s). Neutron 15. A subatomic particle with no charge, that can be found in the nucleus of an atom. Valence Electrons 16. The outer electrons of an atom that can be exchanged or shared with other atoms. Halogen 17. An element of Group 17. Thomson 18. Scientist whose use of cathode ray tubes led to the discovery of the electron. Proton 19. A subatomic particle with positive charge that tells the identity of an atom. Ionization Energy 20. The amount of energy necessary to remove an outermost electron. Rutherford 21. Scientist who performed the gold foil experiment, and concluded that an atom must be composed of mostly empty space with a small, dense, positively-charged nucleus. Reactivity 22. For metals, it is the ability for metals to readily lose electrons. For nonmetals, it is the ability for nonmetals to readily gain electrons. Bright-Line Spectrum 23. An element s fingerprint, produced when electrons move from higher to lower energy levels. Wave-Mechanical Model 24. The most current model of the atom states that electrons are found in orbitals regions of most probable location. Excited State 25. The state of an atom where electrons occupy higher energy levels. 2
Topic 1: Atomic Structure Review 1.) Fill in the following table: Subatomic Particle Relative Charge Relative Mass (amu) Location in Atom Neutron 0 1 inside nucleus Proton +1 1 inside nucleus Electron -1 0 outside nucleus 2.) Draw Bohr diagrams for the following: a.) 24 Mg b.) 24 Mg 2+ c.) 25 Mg 12 p 12 n 12 p 12 n 12 p 13 n 2 8 2 2 8 2 8 2 3.) Draw Lewis dot structures for the following: a.) magnesium atom b.) magnesium cation c.) sulfide anion Mg [Mg] 2+ [ S ] 2 d.) lithium atom Li e.) bromide anion [ Br ] 1 4.) a.) The identity of an element is determined by the number of which sub-atomic particle? proton b.) The mass of an isotope of an element is determine by the number of which two sub-atomic particles? protons and neutrons 3
5.) Fill in the following table. Isotopic Notation Mass # # protons # neutrons # electrons (Element Symbol) 59 27 Co 59 27 32 27 16 2 8 16 8 8 10 70 3 31 70 31 39 28 37 1 17 37 17 20 18 6.) How many oxygen atoms are there in the compound Al(NO 3 ) 3? 9 Use the information below to answer questions 7 and 8. The nucleus of one boron atom has five protons and four neutrons. 7.) Determine the total number of electrons in the boron atom. 5 8.) Determine the total charge of the boron nucleus. +5 9.) What observation in Rutherford s gold foil experiment led to the hypothesis that atoms a.) are composed mostly of empty space? Most of the alpha particles passed through the atoms b.) have a positively charged nucleus? Some of the alpha particles were deflected. 10.) True/False: If the statement is true, tell how you know. If false, correct the statement to make it true. True False True True a.) Atoms of the same element can have different masses. These are isotopes. Most elements on the Periodic Table don t have whole number atomic masses, indicating the atoms are a mixture of isotopes. b.) Atoms of isotopes of an element have different numbers of neutrons. c.) The nucleus of an atom has a positive electrical charge. Protons (positively charged) and neutrons (no charge) are found in the nucleus d.) Atoms are composed mostly of empty space. During Rutherford s gold foil experiment most alpha (positively charged particles) went straight through concluding that the atom is made up of mostly empty space. 4
11.) What does the number 84 represent in the name krypton-84? The mass number or total number of protons plus neutrons. 12.) How can the overall charge on an atom be zero, even though the nucleus is positively charged? The overall charge is determined by the total number of protons (+1) in the nucleus and the total number of electrons ( 1) outside the nucleus. Since an atom has the same number of protons and electrons they add up to zero. 13.) In terms of electrons, explain how Thomson s model, Bohr s model, and the Wave-Mechanical Model differ in their understanding of atomic structure. Thomson s model stated that the electrons were evenly scattered thorughout the positively charged atom while Bohr stated that electrons were kept in specific orbits located at precise distances from the positive nucleus. The quantum or Wave-Mechanical model states that electrons are found in orbitals surrounding the positive nucleaus, and that these orbitals are the most probable (most likely) locations where electrons can be found. 14.) The wave-mechanical model of the atom is required to explain the (1) mass number and atomic number of an atom (2) organization of atoms in a crystal (3) radioactive nature of some atoms (4) spectra of elements with multielectron atoms 15.) What is the mass number of a carbon atom that contains six protons, eight neutrons, and six electrons? (1) 6 (2) 8 (3) 14 (4) 20 16.) Which two particles have opposite charges? (1) an electron and a neutron (3) a proton and a neutron (2) an electron and a proton (4) a proton and a positron 17.) Which total mass is the smallest? (1) the mass of 2 electrons (3) the mass of 1 electron plus the mass of 1 proton (2) the mass of 2 neutrons (4) the mass of 1 neutron plus the mass of 1 electron 18.) Which of these atoms has the greatest number of neutrons in its nucleus? (1) (2) (3) (4) 19.) The table to the right gives information about the nucleus of each of four atoms. How many different elements are represented by the nuclei in the table? (1) 1 (3) 3 (2) 2 (4) 4 5
20.) Chlorine-37 can be represented as 21.) According to the wave-mechanical model of the atom, electrons in an atom (1) travel in defined circles (2) are most likely found in an excited state (3) have a positive charge (4) are located in orbitals outside the nucleus 22.) What can be determined if only the atomic number of an atom is known? (1) the total number of neutrons in the atom, only (2) the total number of protons in the atom, only (3) the total number of protons and the total number of neutrons in the atom (4) the total number of protons and the total number of electrons in the atom 23.) What is the total number of protons in an atom with the electron configuration 2-8-18-32-18-1? (1) 69 (2) 79 (3) 118 (4) 197 24.) The gold foil experiment led to the conclusion that each atom in the foil was composed mostly of empty space because most alpha particles directed at the foil (1) passed through the foil (3) were deflected by the nuclei in gold atoms (2) remained trapped in the foil (4) were deflected by the electrons in gold atoms 25.) In the wave-mechanical model of the atom, orbitals are regions of the most probable locations of (1) protons (2) positrons (3) neutrons (4) electrons 26.) What was concluded about the structure of the atom as the result of the gold foil experiment? (1) A positively charged nucleus is surrounded by positively charged particles. (2) A positively charged nucleus is surrounded by mostly empty space. (3) A negatively charged nucleus is surrounded by positively charged particles. (4) A negatively charged nucleus is surrounded by mostly empty space. 27.) What can be determined if only the atomic number of an atom is known? (1) the total number of neutrons in the atom, only (2) the total number of protons in the atom, only (3) the total number of protons and the total number of neutrons in the atom (4) the total number of protons and the total number of electrons in the atom 28.) Which subatomic particles are located in the nucleus of an He-4 atom? (1) electrons and neutrons (3) neutrons and protons (2) electrons and protons (4) neutrons, protons, and electrons 29.) Which part of a helium atom is positively charged? (1) electron (2) neutron (3) nucleus (4) orbital 30.) What is the total charge of the nucleus of a nitrogen atom? (1) +5 (2) +2 (3) +7 (4) +14 6
31.) In an atom of argon-40, the number of protons (1) equals the number of electrons (3) is less than the number of electrons (2) equals the number of neutrons (4) is greater than the number of electrons 32.) Which quantity identifies an element? (1) atomic number (2) mass number (3) total number of neutrons in an atom of the element (4) total number of valence electrons in an atom of the element 33.) An atom is electrically neutral because the (1) number of protons equals the number of electrons (2) number of protons equals the number of neutrons (3) ratio of the number of neutrons to the number of electrons is 1:1 (4) ratio of the number of neutrons to the number of protons is 2:1 34.) Which two particles make up most of the mass of a hydrogen-2 atom? (1) electron and neutron (3) proton and neutron (2) electron and proton (4) proton and positron 35.) A sample composed only of atoms having the same atomic number is classified as (1) a compound (2) a solution (3) an element (4) a mixture 36.) Which element is a liquid at STP? (1) argon (2) bromine (3) chlorine (4) sulfur 37.) Which Group 15 element exists as diatomic molecules at STP? (1) phosphorus (2) nitrogen (3) bismuth (4) arsenic 38.) The ions that are normally formed from K and Cl have what electron configuration? 2-8-8 This is the same electron configuration as which noble gas? Argon (Ar) 39.) Give the chemical formula of the compound formed by the following ions. a.) aluminum ion and sulfide ion. Al 2 S 3 b.) potassium ion and nitride ion c.) calcium ion and oxide ion K 3 N CaO d.) sodium ion and sulfate ion Na 2 SO 4 e.) ammonium ion and carbonate ion (NH 4 ) 2 CO 3 f.) magnesium ion and nitrate ion Mg(NO 3 ) 2 40.) a.) What is the number of valence electrons in an atom of selenium? 6 b.) What is the total number of electrons in an atom of selenium? 34 7
41.) Give the symbol for one (1) cation and one (1) anion that have the same electron configuration as the noble gas, argon. Possible Cations: K 1+, Ca 2+, Ga 3+ Possible Anions: P 3, S 2, Cl 1 42.) a.) An unknown element X can form a compound with the formula X 2 O. In which group on the Periodic Table could element X be found? The element needs to have a +1 charge (oxidation number) it has to be in Group 1 b.) An unknown element X can form a compound with the formula XBr 3. In which group on the Periodic Table could element X be found? The element needs to have a +3 charge (oxidation number) it has to be in Group 13 43.) What is the total number of electrons in a Mg 2+ ion? (1) 10 (2) 12 (3) 14 (4) 24 44.) What is the total number of valence electrons in an atom of germanium? (1) 8 (2) 2 (3) 14 (4) 4 45.) An atom has seven valence electrons. This atom could be an atom of which element? (1) calcium (2) fluorine (3) oxygen (4) sodium 46.) What is the total number of electrons in an atom of potassium? (1) 18 (2) 19 (3) 20 (4) 39 47.) Which Lewis electron-dot diagram represents calcium oxide? 48.) Which statement explains why sulfur is classified as a Group 16 element? (1) A sulfur atom has 6 valence electrons. (2) A sulfur atom has 16 neutrons. (3) Sulfur is a yellow solid at STP. (4) Sulfur reacts with most metals. 49.) In which compound is the ratio of metal ions to nonmetal ions 1 to 2? (1) calcium bromide (3) calcium phosphide (2) calcium oxide (4) calcium sulfide 50.) A barium atom attains a stable electron configuration when it bonds with (1) one chlorine atom (3) one sodium atom (2) two chlorine atoms (4) two sodium atoms 51.) What is the net charge on an ion that has 9 protons, 11 neutrons, and 10 electrons? (1) 1+ (2) 2+ (3) 1 (4) 2 52.) Which element forms a compound with chlorine with the general formula MCl? (1) Rb (2) Ra (3) Re (4) Rn 8
53.) In the formula X 2 O 5, the symbol X could represent an element in Group (1) 1 (2) 2 (3) 15 (4) 18 54.) The chemical properties of calcium are most similar to the chemical properties of (1) Ar ` (2) K (3) Mg (4) Sc 55.) Which two elements have the most similar chemical properties? (1) Be and Mg (2) Ca and Br (3) Cl and Ar (4) Na and P 56.) Magnesium and calcium have similar chemical properties because a magnesium atom and a calcium atom have the same (1) atomic number (3) total number of electron shells (2) mass number (4) total number of valence electrons 57.) Which Group 14 element is a metalloid? (1) tin (2) silicon (3) lead (4) carbon 58.) An atom in the ground state has a stable valence electron configuration. This atom could be an atom of (1) Al (2) Cl (3) Na (4) Ar 59.) located? (1) 1 (2) 2 (3) 13 (4) 17 Topic 2: Ground vs. Excited States 1.) Draw Bohr diagrams for the following: a.) 32 S in the ground state b.) 32 S in the excited state (many possible answers!) 16 p 16 n 16 p 16 n 2 8 6 2 8 5 1 2.) True/False: If the statement is true, tell how you know. If false, correct the statement to make it true. False a.) When an electron moves from a higher to a lower energy level, the electron releases (emits) energy, producing a bright-line spectrum. True b.) Emission of light occurs when an electron drops from the excited state to the ground state. Energy is released in the form of light when an electron moves from a higher energy level down to a lower energy level. True c.) The amount of energy required to remove the outermost electron from a gaseous atom in the ground state is known as the first ionization energy. This is the definition of ionization energy. 3.) Which of the following represents an excited state of an atom? (Circle all that apply.) Explain how you know. (1) 2-7-1-1 (2) 2-7 (3) 2-8-8-1 (4) 2-8-7-1 Ground state would be 2-8-1 Ground state would be 2-8-8 4.) Which electron configuration represents the electrons of an atom in an excited state? (1) 2-4 (2) 2-6 (3) 2-7-2 (4) 2-8-2 9
5.) The lowest energy level of an atom: (1) is closest to the nucleus and holds up to 8 electrons (2) is closest to the nucleus and holds up to 2 electrons (3) is furthest from the nucleus and holds up to 8 electrons (4) is furthest from the nucleus and holds up to 2 electrons 6.) When an electron moves from a higher to a lower energy level, the electron: (1) absorbs energy, producing a bright-line spectrum. (2) absorbs energy but no bright-line spectrum is produced. (3) releases energy, producing a bright-line spectrum. (4) releases energy but no bright-line spectrum is produced. 7.) Emission of light occurs when an electron (1) drops from a higher to a lower energy level (3) moves around within its orbital (2) jumps from a lower to a higher energy level (4) crashes into the nucleus 8.) Which electron configuration represents an atom in an excited state? (1) 2 7 (2) 2 6 2 (3) 2 8 1 (4) 2 8 8 2 Topic 3: Calculating Weighted Atomic Mass 1.) What are isotopes? Give an example. Atoms of an element with a different mass number due to different amounts of neutrons in the nucleus. Example: Isotopes of Carbon- C-12, C-13, and C-14 2.) What is the atomic mass of the element Q if its isotopes are 45% Q-17, 50% Q-18, and 5% Q-19? 45% = 45/100 =.45 50% = 50/100 =.50 5% = 5/100 =.05 Q-17 = 17 x.45 = 7.65 Q-18 = 18 x.50 = 9.00 Q-19 = 19 x.05 = + 0.95 17.60 amu 3.) The mass of an element is determined by taking a weighted average of all its isotopes. 4.) Naturally occurring bromine consists of two isotopes: 79 Br and 81 Br. a.) How many neutrons are in each isotope? 79 Br contains 44 neutrons and 81 Br contains 46 neutrons. b.) Based on the periodic table, which isotope must be the most abundant? Explain. 79 Br is most abundant because weighted average or atomic mass (79.904) is closer to 79 than 81. 5.) Carbon has three naturally occurring isotopes, C-12, C-13, and C-14. Diamond and graphite are familiar forms of solid carbon. Diamond is one of the hardest substances known, while graphite is a very soft substance. Diamond has a rigid network of bonded atoms. Graphite has atoms bonded in thin layers that are held together by weak forces. Recent experiments have produced new forms of solid carbon called fullerenes. One fullerene, C 60, is a spherical, cage-like molecule of carbon. Determine both the total number of protons and the total number of neutrons in an atom of the naturally occurring carbon isotope with the largest mass number. C-14 has six protons and 8 neutrons 10
Base your answers to questions 6 and 7 on the information below. 6.) State, in terms of the number of subatomic particles, one similarity and one difference between the atoms of these isotopes of sulfur. All isotopes of sulfur contain 16 protons. The isotopes of sulfur differ in the amount of neutrons they contain in the nucleus. 7.) Show a correct numerical setup for calculating the atomic mass of sulfur. S-32 = 31.97 x.9493 = 30.349 S-33 = 32.97 x.0076 = 0.251 S-34 = 33.97 x.0429 = 1.457 S-36 = 35.97 x.0002 = +0.007 amu 8.) The table below shows the number of subatomic particles in atom X and in atom Z. Subatomic Particles in Two Atoms Atom X and atom Z are isotopes of the element (1) aluminum (2) carbon (3) magnesium (4) nitrogen 9.) Which value of an element is calculated using both the mass and the relative abundance of each of the naturally occurring isotopes of this element? (1) atomic number (2) atomic mass (3) half-life (4) molar volume 10.) Which two notations represent different isotopes of the same element? 11
Topic 4: Periodic Trends 1.) Do the following conversions: a. 109.77 ml = 0.10977 L 109.77 ml 1 L = 0.10977 L 1,000 ml b. 52.6 kg = 52,600 g 52.6 kg 1,000 g = 52,600 g 1 kg c. 93.9 g = 93,900 mg 93.9 g 1,000 mg = 93,900 mg 1 g 2.) a. List three physical properties of metals. Malleable, ductile, high melting points, conducts electricity and heat, and has luster b. List three physical properties of non-metals. Brittle, dull, low melting points, and non-conductive c. What is a metalloid? An element that has properties of both a metal and nonmetal. 3.) When combining with non-metallic atoms, metallic atoms will lose electrons to (lose or gain) form positive ions. (positive or negative) 4.) Sulfur atoms can form anions with a 2 in order to get a full octet. (cations or anions) (+ or ) (1, 2, 3, 4) 5.) Which element on the periodic table is the most metallic? Explain using the definition for a metal. Francium (Fr) is the most metallic element. A metal is defined as the ability to lose electrons. Francium most easily loses electrons because of its 7 shells and 1 valence electron. Since the electrons are farther away from its positively charged nucleus they are not held on (attracted) to and are easily lost. 6.) Which element on the periodic table is the most electronegative? Explain using the definition for electronegativity. Fluorine (F) is the most electronegative element. Electronegativity is the ability to attract electrons and fluorine most easily attracts electrons because it has 2 shells, and 7 valence electrons. Since the electrons are close to the positively charged nucleus they are held on (attracted to) strongly and can easily gain electrons. Use the information below for questions 7 through 9. The atomic and ionic radii for sodium and chlorine are shown in the table. 7.) Write the ground state electron configuration for the ion that has a radius of 181 picometers. 2-8-8 8.) Convert the radius of an Na + ion to meters. 1 meter = 1 x 10 +12 pm 102 pm 1 m = 1.02 x 10-10 m or 0.000000000102 m 1 x 10 +12 pm 9.) Explain, in terms of atomic structure, why the radius of an Na atom is larger than the radius of an Na + ion. A sodium atom loses the electron in its outer shell, causing the radius of the ion to be smaller than the radius of the atom. OR An Na atom has three electron shells, but an Na+ ion has only two electron shells. 12
10.) Is the ion formed from the S atom smaller or larger than the S atom itself? larger 11.) The most active metals are contained in which group of the periodic table? Group 1 12.) For the following, circle the element that can be characterized by the given property. a.) transition metal: Ca Al Ag Mg b.) alkali metal: Al Sn Ag Rb c.) largest radius: Mg Ca Sr d.) lowest boiling point: Kr Ni Li e.) metalloid: Cu Sb P Ne f.) most electronegative: F Cl O S 13.) Name two for each of the following: a.) transition metals (Groups 3-12) Possibilities: V, Fe, Co, Ni, Cd, Hg, etc. b.) halogens (Group 17) F, Cl, Br, I, At c.) alkali metals (Group 1) Li, Na, K, Rb, Cs, Fr d.) alkaline earth metals (Group 2) Be, Mg, Ca, Sr, Ba, Ra 14.) a.) According to Table S, how do the following properties change from top to bottom of a group of elements? Atomic size The atomic size increases from top to bottom. Electronegativity The electronegativity decreases from top to bottom. Ionization Energy The ionization energy decreases from top to bottom. b.) According to Table S, how do the following properties change from left to right of a period of elements? Atomic size The atomic size decreases from left to right. Electronegativity The electronegativity increases from left to right. Ionization Energy The ionization energy increases from left to right. 15.) Which element is a metalloid? (1) Al (2) Ar (3) As (4) Au 16.) In the ground state, each atom of an element has two valence electrons. This element has a lower first ionization energy than calcium. Where is this element located on the Periodic Table? (1) Group 1, Period 4 (3) Group 2, Period 3 (2) Group 2, Period 5 (4) Group 3, Period 4 13
17.) An element that is malleable and a good conductor of heat and electricity could have an atomic number of (1) 16 (2) 18 (3) 29 (4) 35 18.) On the modern Periodic Table, the elements are arranged in order of increasing (1) atomic mass (3) mass number (2) atomic number (4) oxidation number 19.) An element that has low first ionization energy and is a good conductivity of heat and electricity is classified as a (1) metal (2) metalloid (3) nonmetal (4) noble gas 20.) How do the atomic radius and metallic properties of sodium compare to the atomic radius and metallic properties of phosphorus? (1) Sodium has a larger atomic radius and is more metallic. (2) Sodium has a larger atomic radius and is less metallic. (3) Sodium has a smaller atomic radius and is more metallic. (4) Sodium has a smaller atomic radius and is less metallic 21.) As atomic number increases within Group 15 on the Periodic Table, atomic radius (1) decreases, only (3) decreases, then increases (2) increases, only (4) increases, then decreases 22.) At STP, which element is solid, brittle, and a poor conductor of electricity? (1) Al (2) K (3) Ne (4) S 23.) Which Group 14 element is classified as a metal? (1) carbon (2) germanium (3) silicon (4) tin 24.) Which element is a solid at STP and a good conductor of electricity? (1) iodine (2) mercury (3) nickel (4) sulfur 25.) Which element has both metallic and nonmetallic properties? (1) Rb (2) Rn (3) Si (4) Sr Topic 5: Structure Determines Properties 1.) Which of the following represent a pair of allotropes? (1) 16 O and 15 O (2) O 0 and O 2- (3) O 2 and O 3 (4) O 2 and S 2 2.)Which statement correctly describes two forms of oxygen, O 2 and O 3? (1) They have identical molecular structures and identical properties. (2) They have identical molecular structures and different properties. (3) They have different molecular structures and identical properties. (4) They have different molecular structures and different properties. 14