Chapter Seven Atomic Structure and Periodicity

Copyright © Houghton Mifflin Company. All rights reserved.7 | 2 Question Which form of electromagnetic radiation has the shortest wavelengths? a)Gamma rays b)Microwaves c)Radio waves d)Infrared radiation e)X-rays

Copyright © Houghton Mifflin Company. All rights reserved.7 | 3 Answer a)Gamma rays Section 7.1, Electromagnetic Radiation The radiation with the shortest wavelength has the highest energy.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 4 Question From the following list of observations, choose the one that most clearly supports the following conclusion: Electrons have wave properties. a)Emission spectrum of hydrogen b)The photoelectric effect c)Scattering of alpha particles by metal foil d)Diffraction e)Cathode “rays”

Copyright © Houghton Mifflin Company. All rights reserved.7 | 5 Answer d)Diffraction Section 7.2, The Nature of Matter Diffraction patterns are produced by waves.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 6 Question From the following list of observations, choose the one that most clearly supports the following conclusion: Electrons in atoms have quantized energies. a)Emission spectrum of hydrogen b)The photoelectric effect c)Scattering of alpha particles by metal foil d)Diffraction e)Cathode “rays”

Copyright © Houghton Mifflin Company. All rights reserved.7 | 7 Answer a) Emission spectrum of hydrogen Section 7.2, The Nature of Matter The emission spectrum shows only certain colors of light, providing support for quantized energy levels.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 8 Question From the following list of observations, choose the one that most clearly supports the following conclusion: de Broglie wavelengths. a)Emission spectrum of hydrogen b)The photoelectric effect c)Scattering of alpha particles by metal foil d)Diffraction e)Cathode “rays”

Copyright © Houghton Mifflin Company. All rights reserved.7 | 9 Answer d) Diffraction Section 7.2, The Nature of Matter Diffraction patterns are produced by waves. The various wavelengths of light are not scattered the same way.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 10 Question Which of the following statements is false? a)The energy of electromagnetic radiation increases as its frequency increases. b)An excited atom can return to its ground state by absorbing electromagnetic radiation. c)An electron in the n = 4 state in the hydrogen atom can go to the n = 2 state by emitting electromagnetic radiation at the appropriate frequency. d)The frequency and the wavelength of electromagnetic radiation are inversely proportional to each other.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 11 Answer b)An excited atom can return to its ground state by absorbing electromagnetic radiation. Section 7.2, The Nature of Matter; Section 7.3, The Atomic Spectrum of Hydrogen An excited atom returns to its ground state by releasing energy in the form of electromagnetic radiation.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 12 Question Which of the following statements is correct? a)For the transitions n 1  n 2, the frequency is larger for H than for He +. b)The ionization energy of the H atom is smaller than the second ionization energy of the He atom. c)The 1s orbital in He + is larger (in the sense that the probability density is shifted outward) than the 1s orbital in H.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 13 Answer b)The ionization energy of the H atom is smaller than the second ionization energy of the He atom. Section 7.4, The Bohr Model In both cases, only one electron is present. For helium, Z = 2; for hydrogen, Z = 1. Ionization energy is related to Z 2, so the second ionization energy for helium is 4 times as great as the ionization energy for the hydrogen atom.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 14 Question For which of the following electron transitions in a hydrogen atom does the light emitted have the longest wavelength? a) n = 4 to n = 3 b)n = 4 to n = 2 c)n = 4 to n = 1 d)n = 3 to n = 2 e)n = 2 to n = 1

Copyright © Houghton Mifflin Company. All rights reserved.7 | 15 Answer a) n = 4 to n = 3 Section 7.4, The Bohr Model Energy is inversely related to wavelength: Thus, the smaller the energy change, the longer the wavelength. The transition n = 4 to n = 3 has the smallest energy change of all of the options.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 16 Question How many electrons can be described by the quantum numbers n = 3, ℓ = 3, m ℓ = 1? a)0 b)2 c)6 d)10 e)14

Copyright © Houghton Mifflin Company. All rights reserved.7 | 17 Answer a)0 Section 7.6, Quantum Numbers Electrons with n = 3 can have values for ℓ of only 0, 1, or 2.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 18 Question A ground-state electron in the hydrogen atom is given just enough energy to get to n = 2. Which orbital will the electron occupy? a)The 2s orbital. b)The 2p x orbital. c)The 2p y orbital. d)The 2p z orbital. e)Each of the above orbitals is equally likely.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 19 Answer e) Each of the above orbitals is equally likely. Section 7.7, Orbital Shapes and Energies Because the hydrogen atom has only one electron, the 2s and 2p orbitals are degenerate.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 20 Question Which of the following combinations of quantum numbers is not allowed? nℓ m ℓ m s a) 110½ b) 300-½ c) 21-1½ d) 43-2-½ e) 420½

Copyright © Houghton Mifflin Company. All rights reserved.7 | 21 Answer a) 1, 1, 0, ½ Section 7.6, Quantum Numbers Electrons with n = 1 can only have 0 as a value for ℓ.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 22 Question How many of the following electron configurations for the species in their ground state are correct? Ca:1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Mg:1s 2 2s 2 2p 6 3s 1 V:[Ar]3s 2 3d 3 As:[Ar]4s 2 3d 10 4p 3 P:1s 2 2s 2 2p 6 3p 5 a)1 b)2 c)3 d)4 e)5

Copyright © Houghton Mifflin Company. All rights reserved.7 | 23 Answer b)2 Section 7.11, The Aufbau Principle and the Periodic Table Ca:1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Mg:1s 2 2s 2 2p 6 3s 2 V:[Ar]4s 2 3d 3 As:[Ar]4s 2 3d 10 4p 3 P:1s 2 2s 2 2p 6 3s 2 3p 5

Copyright © Houghton Mifflin Company. All rights reserved.7 | 24 Question In which of the following groups do all the elements have the same number of valence electrons? a)P, S, Cl b)Ag, Cd, Ar c)Na, Ca, Ba d)P, As, Se e)None of these

Copyright © Houghton Mifflin Company. All rights reserved.7 | 25 Answer e)None of these Section 7.11, The Aufbau Principle and the Periodic Table Elements will have the same number of valence electrons if they are members of the same group on the periodic table.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 26 Question Element X has a ground-state valence electron configuration of ns 2 np 5. What is the most likely formula for the compound composed of element X and nitrogen? a)NX b)NX 7 c)NX 2 d)NX 3 e)NX 5

Copyright © Houghton Mifflin Company. All rights reserved.7 | 27 Answer d) NX 3 Section 7.11, The Aufbau Principle and the Periodic Table An element with the valence electron configuration ns 2 np 5 is a halogen.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 28 Question Of the following elements, which has occupied d orbitals in its ground-state neutral atoms? a)Ba b)Ca c)Si d)P e)Cl

Copyright © Houghton Mifflin Company. All rights reserved.7 | 29 Answer a)Ba Section 7.11, The Aufbau Principle and the Periodic Table For an element to have occupied d orbitals in its ground-state neutral atoms, it must have an atomic number greater than 20.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 30 Question Consider the following orderings: I.Al < Si < P < Cl II.Be < Mg < Ca < Sr III.I < Br < Cl < F IV.Na + < Mg 2+ < Al 3+ < Si 4+ Which of these give(s) a correct trend in size? a)I b)II c)III d)IV e)At least two of the above give a correct trend in size.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 31 Answer b)II Section 7.12, Periodic Trends in Atomic Properties The sizes of atoms increase going down in groups and decrease going across in periods. Ionic size decreases with increase in positive charge.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 32 Question Consider the following orderings: I.Al < Si < P < Cl II.Be < Mg < Ca < Sr III.I < Br < Cl < F IV.Na + < Mg 2+ < Al 3+ < Si 4+ Which of these give(s) a correct trend in ionization energy? a)III b)I, II c)I, IV d)I, III, IV

Copyright © Houghton Mifflin Company. All rights reserved.7 | 33 Answer d)I, III, IV Section 7.12, Periodic Trends in Atomic Properties Ionization energy increases with increased positive charge and decreases going down in a group. Going across in a period, ionization energy tends to increase, albeit with some variations.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 34 Question The first ionization energy of magnesium is approximately 700 kJ/mol. What is a good estimate for the second ionization energy of magnesium? a)700 kJ/mol b)1400 kJ/mol c)70,000 kJ/mol d)-700 kJ/mol e)-1400 kJ/mol

Copyright © Houghton Mifflin Company. All rights reserved.7 | 35 Answer b)1400 kJ/mol Section 7.12, Periodic Trends in Atomic Properties The second ionization energy should be larger than the first ionization energy, because the electron is being taken from a positive ion. In this case, the second electron is taken from the same energy level as the first electron. Thus, while the second IE should be greater, it will not be as great as that shown in choice (c).

Copyright © Houghton Mifflin Company. All rights reserved.7 | 36 Question Which of the following statements concerning second ionization energy values is true? a)The second ionization energy of Al is higher than that of Mg because Mg wants to lose the second electron, so it is easier to take the second electron away. b)The second ionization energy of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton. c)The second ionization energy of Al is lower than that of Mg because Mg wants to lose the second electron, so the energy change is greater. d)The second ionization energy of Al is lower than that of Mg because the second electron taken from Al is in a p orbital, so it is easier to remove. e)The second ionization energies are equal for Al and Mg.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 37 Answer b)The second ionization energy of Al is higher than that of Mg because the electrons are taken from the same energy level, but the Al atom has one more proton. Section 7.12, Periodic Trends in Atomic Properties In both cases, the electron is taken from a 3s orbital.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 38 Question For the atoms Li, N, F, and Na, which of the following is the correct order from smallest to largest atomic radius? a)Na, F, N, Li b)Na, Li, N, F c)Li, N, F, Na d)N, F, Na, Li e)F, N, Li, Na

Copyright © Houghton Mifflin Company. All rights reserved.7 | 39 Answer e) F, N, Li, Na Section 7.12, Periodic Trends in Atomic Properties Atomic radius decreases going across a row of the periodic table and increases going down a column of the periodic table.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 40 Question Which of the following correctly ranks the ionization energies of O, F, Na, S, and Cs from smallest to largest? a)Cs, Na, S, O, F b)Cs, S, Na, O, F c)F, O, Na, S, Cs d)F, O, S, Na, Cs e)Na, S, Cs, F, O

Copyright © Houghton Mifflin Company. All rights reserved.7 | 41 Answer a) Cs, Na, S, O, F Section 7.12, Periodic Trends in Atomic Properties Ionization energy increases going across a row of the periodic table and decreases going down a column of the periodic table.

Copyright © Houghton Mifflin Company. All rights reserved.7 | 42 Question Sodium losing an electron is an ________ process and fluorine losing an electron is an _______ process. a)endothermic; exothermic b)exothermic; endothermic c)endothermic; endothermic d)exothermic; exothermic

Copyright © Houghton Mifflin Company. All rights reserved.7 | 43 Answer c)endothermic; endothermic Section 7.12, Periodic Trends in Atomic Properties Losing an electron from an atom requires energy, which means this reaction is endothermic.