CHAPTER 3:

THE STRUCTURE OF THE ATOM

The following information is often presented on the first page of exams covering this chapter under the heading: "potentially useful information."

N = 6.022 x 1023 particles per mole     h = 6.626 x 10-34 J-s

c = 2.998 x 108 m/sRH = 1.097 x 10-2 nm-1 = 2.18 x 10-18 J

E = - k/n2                                                 ΔE = RH(1/n12 - 1/n22)

Structure of the Atom

3-1. How many electrons are present in the 77Se2- ion?

(a) 32 (b) 34 (c) 43 (d) 77 (e) none of these

Answer: (e)

3-2. How many electrons are present in the 136Ba2+ ion?

(a) 56 (b) 58 (c) 78 (d) 134 (e) none of these

Answer: (e)

3-3. Calculate the number of electrons on a P3- ion if the atomic weight of phosphorus is 31 amu and the atomic number of this element is 15.

(a) 12 (b) 15 (c) 18 (d) 31 (e) 34

Answer: (c)

3-4. Calculate the number of electrons on a Ce4+ ion if the atomic number of this element is 58 and the mass of the ion is 140 amu.

(a) 54 (b) 58 (c) 62 (d) 136 (e) 140

Answer: (a)

3-5. Which has the largest charge to mass ratio:

(a) a proton (b) a neutron (c) an α-particle

(d) an electron (e) an x-ray

Answer: (d)

3-6. Which of the following postulates of Dalton's atomic theory is still valid today?

(I) Matter consists of particles called atoms.

(II) Atoms are indestructible and indivisible.

(III) All atoms of an element are identical.

(IV) Atoms of different elements differ in mass.

(V) When the atoms of different elements combine to form compounds they combine in simple whole number ratios.

(a) All of these statements are still valid today.

(b) I and II are still valid, but not III, IV and V.

(c) I, II and III are still valid, but not IV and V.

(d) I, IV and V are still valid, but not II and III.

(e) II and III are still valid, but not I, IV and V.

Answer: (d)

3-7. Which describes the difference between the 12C, 13C and 14C isotopes of carbon?

(a) They have the same number of protons but different numbers of electrons.

(b) They have the same number of neutrons but different numbers of electrons.

(c) They have the same number of electrons but different numbers of protons.

(d) They have the same number of protons but different numbers of neutrons.

(e) They have the same number of protons, electrons, and neutrons but different atomic masses.

Answer: (d)

3-8. What would you describe as the key result of the Rutherford experiment, in which a metal target was bombarded with α-particles?

(a) The α-particles were able to pass through the target.

(b) The particles were found to knock electrons out of the target.

(c) Some of the α-particles were deflected through large angles.

(d) Flashes of light were emitted when the α-particles hit the ZnS screen after they passed through the target.

(e) The experiment showed the need for better α-particle detectors.

Answer: (c)

3-9. What do we mean when we say that "The energy of the electron in an atom is quantized?"

(a) The electron has a very small energy.

(b) The energy of the electron is proportional to the mass of the nucleus.

(c) When an electron changes it energy, it emits a quantum of light.

(d) The energy of the electron can have certain fixed energies and not others.

(e) The electron must be a wave.

Answer: (d)

3-10. Which of the following statements is inconsistent with modern quantum mechanics?

(a) The hydrogen atom emits light at only a limited number of discrete frequencies.

(b) In the ground state of the hydrogen atom the electron is constrained to a circular orbit.

(c) The energy of the hydrogen atom is quantized.

(d) No two electrons in an atom can have the same set of four quantum numbers.      (e) The spin quantum number has a half-integral value.

Answer: (b)

3-11. The earth is constantly bombarded by cosmic rays emitted by the sun. The total energy received in the form of cosmic rays is small — no more than the energy received by the planet from starlight. But the energy of a single cosmic ray is very large, on the order of 200 million kJ/mol. These highly energetic rays react with atoms in the atmosphere to produce neutrons that then react with nitrogen atoms in the atmosphere to produce 14C, which decays back to 14N with a half-life of 5730 years by emitting an electron. What is the difference between 14C and 14N atoms?

(a) They have the same number of protons but different numbers of neutrons.

(b) They have the same number of neutrons but different numbers of protons.

(c) They have the same number of neutrons and protons but different numbers of electrons

(d) 14N has one more proton and one less neutron than 14C

(e) 14N has one more neutron and one less proton than 14C

Answer: (d)

3-12. In theory, any atom lighter than the 56Fe isotope of iron should undergo a nuclear fusion reaction if the temperature is hot enough to ignite this thermonuclear reaction. Because these reactions only occur at temperatures on the order of 107 K, we probably don’t have to worry about the carbon atoms in our bodies undergoing spontaneous fusion reactions to turn into iron metal. How many electrons, protons, and neutrons could be found in an 56Fe3+ ion formed during a supernova explosion?

(a) 23 e-, 23 p+, and 33 n0          (b) 23 e-, 26 p+, and 30 n0

(c) 26 e-, 23 p+, and 33 n0          (d) 29 e-, 26 p+, and 30 n0

(e) 26 e-, 29 p+, and 27 n0

Answer: (b)

Electromagnetic Radiation

3-13. What is the wavelength in centimeters of light that has a frequency of 2.33 x 1015 s-1? (a) 6.99 x 1025 cm (b) 7.77 x 104 cm (c) 1290 cm (d) 1.29 x 10-5 cm

(e) none of the above

Answer: (d)

3-14. A helium-neon laser emits light with a wavelength of 6328 Å. What is the energy of a 6328 Å photon in joules?

(a) 2.179 x 10-19 J (b) 3.139 x 10-19 J (c) 5.448 x 10-19 J

(d) 6.328 x 10-19 J (e) 2.179 x 10-18 J

Answer: (b)

3-15. If green light has a frequency of 5.0 x 1014 s-1 what is the wavelength (in meters) of this light?

(a) 6.7 x 10-24 (b) 2.0 x 10-15 (c) 6.0 x 10-7

(d) 3.0 x 108 (e) none of the above

Answer: (c)

3-16. If x-rays have a shorter wavelength than ultraviolet-rays, which of the following statements is true?

(a) x-rays have smaller frequencies than UV-rays.

(b) x-rays travel faster than UV-rays.

(c) x-rays have more energy than UV-rays.

(d) x-rays have a larger amplitude than UV-rays.

(e) none of the above statements are true.

Answer: (c)

3-17. Which of the following could convert a nonionizing form of electromagnetic radiation into a form of ionizing radiation?

(a) decreasing the wavelength of the radiation.

(b) decreasing the energy of the radiation.

(c) decreasing the frequency of the radiation.

(d) all of the above are true.

(e) none of the above are true.

Answer: (a)

3-18. In a 23.490 kilogauss magnetic field, 13C nuclei absorb electromagnetic radiation in the RF (radio) portion of the spectrum at a frequency of 25.147 MHz (25.147 x 106 s-1.) Calculate the wavelength of this radiation.

(a) longer than 10 meters                      (b) between 10 and 0.10 meters

(c) between 0.10 and 10-4 meters         (d) between 10-4 and 10-6

(e) shorter than 10-6 meters

Answer: (a)

3-19. O2 molecules can dissociate to form O atoms by absorbing electromagnetic radiation. If it takes 498 kJ to dissociate one mole of O2 molecules to form two moles of O atoms, what would be the wavelength of the radiation that would have just enough energy to decompose O2 molecules to O atoms? In what portion of the electromagnetic spectrum would this wavelength be found?

(a) radiowave (b) microwave (c) infrared (d) visible (e) ultraviolet

Answer: (e)

3-20. In 1814 Fraunhofer observed a series of dark lines in the sun's spectrum, which he labeled A through H. About 50 years later, Gustav Kirchhoff noticed that the wavelength of light given off when sodium salts are added to a flame is the same as the wavelength of the D line in Fraunhofer's spectrum. He concluded that certain substances give off light when heated that has the same wavelength as the light absorbed under other conditions. The wavelength of the characteristic yellow-orange light emitted by sodium ions in a burner flame is 589.5923 nm. What is the energy of this light, in units of kJ/mol?

(a) Less than 1 kJ/mol (b) Between 1 and 10 kJ/mol

(c) Between 10 and 100 kJ/mol (d) Between 100 and 1000 kJ/mol

(e) More than 1000 kJ/mol

Answer: (d)

3-21. There is a fundamental difference between the long wavelength IR radiation given off by the toy ovens sold at Toys ‘R Us and the shorter wavelength UV radiation emitted by the tanning booths at your local strip mall. Which of the following statements is true?

(a) IR radiation has a higher frequency than UV radiation.

(b) IR radiation carries more energy per photon than UV radiation.

(c) IR radiation carries a larger amplitude than UV radiation.

(d) IR radiation travels slower than UV radiation.

(e) None of the above statements are true.

Answer: (e)

3-22. A cheap spectrophotometer can be made using a light-emitting diode as the source of the light. Assume that you build one of these spectrometers using an LED that gives off green light with a wavelength of 520 nm. What is the energy of a photon of this green light?

(a) 1.15 x 10-34 J (b) 1.03 x 10-22 J (c) 3.82 x 10-21 J

(d) 3.82 x 10-19 J (e) none of the above

Answer: (d)

3-23. In what portion of the electromagnetic spectrum are you likely to find the radiation that carries just enough energy to be dangerous to life because it can ionize the water that is so important to living organisms?

(a) Radio/TV waves, λ ≈ 10 - 0.1 m

(b) Microwaves, λ ≈ 0.01 - 10-4 m

(c) Ultraviolet, λ ≈10-7 - 10-9 m

(d) X-rays, λ ≈ 10-10 - 10-12 m

(e) γ-rays, λ ≈ 10-12 - 10-14 m

Answer: (c)

3-24. A recent article in Scientific American notes that life would be impossible on any planet close enough to the Sun to boil water, or far enough from the Sun that water froze. It also argues that the Earth is in one of the few parts of the galaxy where life could exist. Too close to the core, and either collisions with other objects would the destroy the planet or cosmic radiation from neighboring stars would destroy life. To far from the sun, and there wouldn’t be enough of the elements needed to form a planet. Let’s assume that radiation becomes particularly dangerous to life when it carries enough energy to ionize a water molecule when it is absorbed.

H2O(l) + hν ➝ H2O+ + e-ΔH = 1200 kJ/mol

Use Avogadro’s number and Planck’s constant to calculate the frequency of this radiation to one significant figure. (Hint: Place close attention to units!)

(a) 3 x 109 s-1          (b) 3 x 1012 s-1        (c) 3 x 1015 s-1

(d) 3 x 1018 s-1        (e) 3 x 1021 s-1

Answer: (b)

Bohr Model of the Atom

3-25. The band structure of the emission spectrum of the hydrogen atom suggests that:

(a) The atom is composed of a small positive nucleus and electrons.

(b) There are many electrons in a hydrogen atom.

(c) The position and energy of an electron cannot be determined simultaneously.

(d) The energies of electrons are quantized.

Answer: (d)

3-26. Which of the following statements about the Bohr model is wrong?

(a) The energy of the atom is quantized

(b) All possible wavelengths can occur in the emission spectrum since n runs from 1 to infinity

(c) The angular momentum of the electron is quantized

(d) All quantized energies are negative.

Answer: (b)

3-27. Which of the following transitions in the spectrum of the hydrogen atom results in the absorption of a photon with the largest energy?

(a) n = 2 to n = 3 (b) n = 2 to n = 4 (c) n = 1 to n = 4

(d) n = 3 to n = 1 (e) n = 7 to n = 1

Answer: (c)

3-28. Which transition in the spectrum of the hydrogen atom results in the emission of light with the longest wavelength?

(a) n = 3 to n = 2 (b) n = 3 to n = 1 (c) n = 5 to n = 4

(d) n = 2 to n = 3 (e) n = 1 to n = 3

Answer: (c)

3-29. What is the energy of the light emitted when an electron falls from the n = 4 to the n = 2 orbit in the hydrogen atom?

(a) 4.09 x 10-19 J (b) 5.45 x 10-18 J (c) 4.36 x 10-18 J

(d) 2.62 x 10-17 J (e) none of the above

Answer: (a)

3-30. If a laser operated on the n = 5 to n = 2 transition of a H atom, what wavelength photon would be emitted?

(a) 380 nm (b) 434 nm (c) 1950 nm (d) 3910 nm (e) none of the above

Answer: (b)

Quantum Numbers

3-31. Which of the following quantum numbers is used to describe the orientation of an orbital in space?

(a) n (b) l (c) m (d) s

(e) none of these quantum numbers describe the orientation of an orbital in space.

Answer: (c)

3-32. Which of the following quantum numbers can have a value that is not an integer?

(a) n (b) l (c) m (d) s

(e) none of the quantum numbers can have any value that is not an integer

Answer: (d)

3-33. What kind of orbital is described by the quantum numbers: n = 4, l = 2, m = -1?

(a) 4s (b) 4p (c) 4d (d) 4f (e) none of these

Answer: (c)

3-34. Orbitals for which l = 1 are described by which of the following symbols?

(a) s (b) p (c) d (d) f (e) g

Answer: (b)

3-35. The Pauli exclusion principle states that:

(a) No two electrons in an atom can have the same spin.

(b) No two electrons in an atom can occupy the same orbital.

(c) Two electrons in the same orbital have identical values of the spin quantum number.

(d) No two electrons in an atom can have the same set of four quantum numbers.      (e) No two electrons in an atom can have the same principal quantum number.

Answer: (d)

3-36. In the absence of an external magnetic field, the energy of an electron in an orbital in a lithium atom is determined by which pair of quantum numbers?

(a) n and l (b) n and m (c) n and s (d) l and m (e) m and s

Answer: (a)

3-37. Two orbitals are said to be degenerate if they:

(a) Contain the same number of electrons

(b) Have the same value for the angular quantum number, l, and different values of the principal quantum-number, n

(c) Have the same set of three quantum numbers, n, and m, but have different values of the s quantum number

(d) Have the same energy

(e) Contain the same number of unpaired electrons

Answer: (d)

3-38. What is the maximum number of electrons that can be accommodated in the subshell for which n = 3 and l = 2?

(a) 2 (b) 6 (c) 10 (d) 14 (e) 18

Answer: (c)

3-39. Calculate the maximum number of electrons that can fit into the n = 4 shell of orbitals. (a) 6 (b) 8 (c) 18 (d) 16 (e) 32

Answer: (e)

3-40. Which of the following selection rules for quantum numbers is incorrectly stated?

(a) n is any integer greater than or equal to zero.

(b) l is any integer between zero and n - l.

(c) m is any integer between -l and +l.

(d) s is either +½ or -½.

(e) All of the above selection rules are correctly stated.

Answer: (a)

3-41. Which of the following atomic orbitals doesn’t exist?

(a) 3f (b) 3p (c) 5f (d) 5d (e) 6s

Answer: (a)

3-42. Which is a legitimate set of n, l, m and s quantum numbers?

(a) 0,0,0,½ (b) 8,4,-3,-½ (c) 3,3,2,+½ (d) 2,1,-2,-½ (e) 5,3,3,-1

Answer: (b)

3-43. Which set of n, l, m and s quantum numbers is allowed?

(a) 4,-2,-1,½ (b) 4,2,3,½ (c) 4,3,0,1 (d) 4,0,0,-½

Answer: (d)

3-44. Which of the following sets of n, l, m and s quantum numbers isn’t allowed?

(a) 1,1,0,+½ (b) 2,0,0,+½ (c) 3,2,1,-½ (d) 4,1,-1,+½ (e) 5,3,2,-½

Answer: (a)

3-45. Which set of quantum numbers can be used to describe a 2p electron?

(a) 2,1,0,-½ (b) 2,0,0,½ (c) 2,2,1,½ (d) 3,2,1,-½ (e) 3,1,0,½

Answer: (a)

3-46. How many electrons can be placed in a 3d orbital?

(a) 2 (b) 6 (c) 8 (d) 10 (e) 18

Answer: (a)

3-47. What is the maximum number of unpaired electrons that can be accommodated in a 5d subshell?

(a) 3 (b) 5 (c) 6 (d) 7 (e) 10

Answer: (b)

3-48. When Schrödinger’s wave mechanics model is applied to an isolated atom in the gas phase, the energy of an electron in an orbital on the atom is determined by which pair of quantum numbers?

(a) n and l (b) n and m (c) n and s (d) l and m (e) m and s

Answer: (a)

Aufbau Principle

3-49. Which of the following is an incorrect order of increasing energy of the atomic orbitals?

(a) 3s < 4s < 5s (b) 5s < 5p < 5d (c) 5s < 4d < 5p (d) 5p < 6s < 4f

(e) None of these are incorrect

Answer: (e)

3-50. Which set of orbitals is arranged in increasing order of energy?

(a) 3d < 4s < 4p < 5s < 4d             (b) 3d < 4s < 4p < 4d < 5s

(c) 4s < 3d < 4p < 5s < 4d              (d) 4s < 3d < 4p < 4d < 5s

(e) 3d < 4s < 4p < 4d < 5s

Answer: (c)

3-51. Which of the following sets of atomic orbitals are degenerate for a lithium atom?

(a) 3s, 3px, 3dz2               (b) 2px, 2py, 2pz

(c) 2px, 3px, 4px                 (d) None of these sets of orbitals are degenerate.

(e) All of these sets of orbitals are degenerate.

Answer: (b)

3-52. When atomic orbitals are filled according to the Aufbau principle, the 6p orbitals are filled immediately after the:

(a) 4f (b) 5d (c) 6s (d) 7s orbitals

Answer: (b)

3-53. Which of the following subshells of orbitals is filled first when electrons are added to the atomic orbitals on a xenon atom?

(a) 4d (b) 4f (c) 5s (d) 5p (e) 5d

Answer: (c)

3-54. Which of the following orbitals would be filled first when electrons are added to a gold atom?

(a) 4f (b) 5d (c) 6s (d) 6p (e) 6d

Answer: (c)

3-55. In what group of the periodic table would an element with the following electron configuration belong?

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1

(a) Group IA (b) Group IlIA (c) Group VA

(d) Group VIIA (e) none of the above

Answer: (b)

3-56. A single atom of element 109 has been synthesized. Use the Aufbau principle to predict the electronic configuration of this element. Which of the following elements would 109 most resemble?

(a) Ta (b) Re (c) Ir (d) Au (e) Tl

Answer: (c)

3-57. A single atom of element 114 was recently synthesized. Use the Aufbau principle to predict the electronic configuration of this element. Which of the following elements would 114 most resemble?

(a) Au (b) Hg (c) Tl (d) Pb (e) Po

Answer: (d)

3-58. Theoreticians predict that the element with atomic number 120 will be more stable than the elements recently discovered with atomic numbers between 103 and 109. On the basis of the Aufbau principle, and the order of filling of atomic orbitals, the chemistry of this element should most closely resemble the chemistry of which of the following?

(a) Ra, Group IIA (b) Pb, Group IVA (c) Po, Group VIA

(d) Rn in Group VIIIA (e) One of the transition metals between La and Hg

Answer: (a)

3-59. In row 6 of the Periodic table, the series of elements which differ in the number of electrons contained in f orbitals:

(a) begins with Cs and ends with Rn      (b) begins with La and ends with Hg

(c) begins with Tl and ends with Rn        (d) begins with La and ends with Rn

(e) begins with Ce and ends with Lu.

Answer: (b)

3-60. Which neutral atom has the most unpaired electrons?

(a) Na (b) Al (c) Si (d) P (e) S

Answer: (d)

3-61. Which atom contains the largest number of unpaired electrons?

(a) B (b) N (c) F (d) Ti (e) Cu

Answer: (b)

3-62. Which atom or ion has the largest number of unpaired electrons?

(a) Li+ (b) B (c) C4- (d) N (e) O2-

Answer: (d)

3-63. Which element has the largest number of electrons for which the angular quantum number is equal to 1?

(a) He (b) F (c) S (d) As (e) Zn

Answer: (d)

3-64. A possible set of quantum numbers for the last electron added to form a gallium atom (Z = 31) in its ground state is:

(a) 3, 1, 0, -½ (b) 3, 2, 1, ½ (c) 4, 0, 0, ½

(d) 4, 1, 1, ½ (e) 4, 2, 2, ½

Answer: (d)

3-65. A possible set of quantum numbers for the last electron added to form an As3+ ion is:

(a) 3, 1, -1, ½ (b) 4, 0, 0, -½ (c) 3, 2, 0, ½

(d) 4, 1, -1, ½ (e) 5, 0, 0, ½

Answer: (c)

3-66. The outermost or highest energy electron in element 105 could be characterized by which of the following sets of n, l, m and s quantum numbers?

(a) 7, 3, -3, -½ (b) 6, 3, -1, -½ (c) 6, 2, 0, ½ (d) 5, 3, -1, -½

Answer: (c)

3-67. Which of the following describes a possible set of quantum numbers for the last electron added to form an aluminum atom when atomic orbitals are filled?

(a) 1, 0, 0, +½ (b) 2, 0, 0, +½ (c) 2, l, 1, +½

(d) 3, 0, 0, +½ (e) 3, 1, 1, +½

Answer: (e)

3-68. Which of the following sets of n, l, m and s quantum numbers could describe the electron removed from a neutral Al atom when the first ionization energy of aluminum is measured?

(a) 1, 0, 0, +½ (b) 2, 0, 0, +½ (c) 2, 1, 1, +½ (d) 3, 0, 0, +½ (e) 3, 1, l, +½

Answer: (e)

Electron Configurations

3-69. An element with the electron configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2 4d10 5p3 would belong in which group or family of the periodic table?

(a) Group IA (b) Group IIIA (c) Group IVA

(d) Group VA (e) Group VIIA

Answer: (d)

3-70. Which electron configuration for carbon would satisfy Hund's rules?

(a) 1s2 2s2 2px2 2py0 2pz0

(b) 1s2 2s2 2px1 2py1 2pz0

(c) 1s2 2s2 2px1 2py1 2pz1

(d) 1s2 2s2 2px2 2py1 2pz1

(e) none of these configurations satisfy Hund's rules.

Answer: (b)

3-71. What is the ground state electronic configuration of a fluorine atom?

(a) 1s2 2s2 2p5 (b) 1s2 2s2 2p6

(c) 1s2 2s2 2p7 (d) 1s2 2s2 2p6 3s1

(e) none of the above

Answer: (a)

3-72. What is the value of x in the following electron configuration for silicon?

1s2 2s2 2p6 3s2 3px

(a) 1 (b) 2 (c) 3 (d) 4 (e) 6

Answer: (b)

3-73. What is the correct electron configuration for the Ti atom?

(a) 1s2 2s2 2p6 3s2 3p6 3d4          (b) [Ar] 4s2 4d2

(c) [Ar] 4d4                                   (d) 1s2 2s2 2p6 3s2 3d2

(e) [Ar] 4s2 3d2

Answer: (e)

3-74. Which of the following would have the electron configuration:

1s2 2s2 2p6 3s2 3p6 3d4

(a) Ca2+ (b) Cr2+ (c) Fe2+ (d) Ti2+ (e) none of these

Answer: (b)

3-75. What is the correct electron configuration for the P3+ ion?

(a) [Ne] (b) [Ne] 3s2 (c) [Ne] 3s2 3p3 (d) [Ne] 3s2 3p6

Answer: (b)

3-76. What is the electron configuration for the bromide ion, Br-?

(a) [Ar] 4s2 4p5 (b) [Ar] 4s2 3d10 4p7 (c) [Ar] 4s2 3d10 4p5

(d) [Ar] 4s2 3d10 4p6 (e) [Ar] 4s2 3d10 3p6

Answer: (d)

3-77. Which of the following describes the electron configuration for the Sn2+ ion?

(a) [Kr] 4d10 (b) [Kr] 5s2 (c) [Kr] 5s2 5p2

(d) [Kr] 5s2 4d10 (e) [Kr] 5s2 4d10 5p2

Answer: (d)

3-78. What is the electronic configuration of the Alx+ ion in the ionic compound Al2O3?

(a) 1s2 2s2 2p6 (b) 1s2 2s2 2p6 3s2 (c) 1s2 2s2 2p6 3s2 3p1

(d) 1s2 2s2 2p6 3s2 3p4 (e)1s2 2s2 2p6 3s2 3p6

Answer: (a)

3-79. If the X2- ion has no unpaired electrons, in what Group does element X belong?

(a) IA (b) IIA (c) IVA (d) VIA (e) VIIA

Answer: (d)

AVEE/Ionization Energies

3-80. The results of photoelectron spectroscopy studies of the last four elements in the 2nd row of the periodic table are given below.

Element        1s                 2s                 2p

N39.62.451.40

O52.63.121.31

F67.23.881.68

Ne84.04.682.08

Which of the following statements is correct?

(a) The average valence electron energy for N is larger than O, F, or Ne.

(b) The average valence electron energy for O is larger than N, F, or Ne.

(c) The average valence electron energy for F is larger than N, O, or Ne.

(d) The average valence electron energy for Ne is larger than N, O, or F.

(e) The average valence electron energy is the same for all four elements.

Answer: (d)

3-81. If you believe that the average valence electron energy measures the ability of an atom to hold onto its valence electrons, and therefore the ability of the atom to compete for electrons in any bond it might form, which of these atoms should be the most electronegative?

(a) N (b) O (c) F (d) Ne

(e) These elements all have the same electronegativity.

Answer: (d)

3-82. The first ionization energy of the first six elements in the periodic table are given below.

H        1312.0 kJ/mol

He      2372.3

Li         520.2

Be       899.4

B         800.6

C        1086.4

Why is the 1st ionization energy of B smaller than Be?

(a) Because the 1st IE decreases as we go across a row of the periodic table from left to right

(b) Because the nucleus of a B (Z = 5) atom contains fewer protons than the nucleus of a Be (Z = 4) atom.

(c) Because the outermost electron on B is coming from a 2p, not a 2s orbital.

(d) Because the atomic number of B is odd, whereas the atomic number of Be is even.

(e) For the same reason that the 1st IE of He is larger than that of H.

3-83. If a powerful enough source of energy is used in the PES experiment, it is possible to measure the energy required to remove the 2nd, 3rd, 4th, and so on, electrons from an atom. Which of the following elements would have the largest fourth ionization energy?

(a) Al (b) Si (c) P (d) S (e) Cl

Answer: (a)