CH 14

Chapter 14: Covalent Bonding: Orbitals
1. Which of the following molecules contains a nitrogen atom that is sp2 hybridized?
A) NCl 3
B) NO 2 –
C) N 2
D) HCN
E) C 2 N 2
ANS: B PTS: 1 DIF: easy TOP: 14.1
KEY: general chemistry | bonding | bonding theories | hybridization
2. Consider the structure of glycine, the simplest amino acid:
What is the total number of π bonds in the molecule?

A) 0
B) 1/2
C) 1
D) 2
E) More information is needed.
ANS: C PTS: 1 DIF: easy TOP: 14.1
KEY: general chemistry | bonding | bonding theories | multiple bonds
3. What is the hybridization of I in the molecule IF 3 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
ANS: D PTS: 1 DIF: easy TOP: 14.1
4. What is the hybridization of S in the molecule H 2 S?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
5. What is the hybridization of C in the ion CN–?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
ANS: A PTS: 1 DIF: easy TOP: 14.1
6. Atoms that are sp3 hybridized form ____ pi bond(s).

A) 0
B) 1
C) 2
D) 3
E) 4
7. What is the hybridization of the central atom in SF 6 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
ANS: E PTS: 1 DIF: easy TOP: 14.1
8. What is the hybridization of the central atom in PCl 4 +?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
9. What is the hybridization of the central atom in ICl 5 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
10. What is the hybridization of the central atom in SF 4 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
11. What is the hybridization of I in ICl 2 +?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
12. Consider the following molecule. (Lone pairs are not drawn in.)
Specify the hybridization of each carbon atom (in numeric order: C-1 C-2 C-3 C-4 C-
5).
A) sp2 sp2 sp2 sp3 sp
B) sp2 sp2 sp2 sp3 sp3
C) sp2 sp2 sp3 sp3 sp
D) sp2 ssp2 sp3 sp3 sp3
2
E) sp sp sp sp sp
13. What is the hybridization of the phosphorus atom in PCl 4 +?

A) dsp2
B) sp2
C) d2sp3
D) sp2d
E) sp3
14. What is the hybridization of the central I atom in the molecule ICl 5 ?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
15. Which of the following has a central atom that is dsp3 hybridized?
A) SCl 4 –
B) SF 4
C) CBr 4
D) SBr 6
E) SO 3
16. What is the hybridization of the B atom in the molecule BF 3 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
17. What is the hybridization of the I atom in the molecule IF 5 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
Consider the following molecule. (Lone pairs are not drawn in.)
18. What is the hybridization of the carbon atom that is double-bonded to oxygen?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
19. What is the hybridization of the carbon atom that is bonded to chlorine?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
ANS: C PTS: 1 DIF: moderate TOP: 14.1
20. What is the hybridization of the nitrogen atom?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
ANS: A PTS: 1 DIF: moderate TOP: 14.1
21. What is the hybridization of the oxygen atom?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
ANS: B PTS: 1 DIF: moderate TOP: 14.1
22. Which of the following has two π bonds?

A) C 2 H 6
B) C 2 H 4
C) C 2 H 2
D) at least two of these
E) none of these
23. Consider the following Lewis structure. (Lone pairs are not drawn in.)
Which statement about the molecule is false?

A) There are 10 sigma and 2 pi bonds.
B) C-2 is sp2 hybridized with bond angles of 120.
C) Oxygen is sp3 hybridized.
D) This molecule contains 28 valence electrons.
E) There are some H–C–H bond angles of about 109° in the molecule.
KEY: general chemistry | bonding | bonding theories
Tetracyanoethylene has the skeleton shown here:
From its Lewis structure, determine the following.
24. How many sigma bonds and how many pi bonds are in the molecule?
A) 5 sigma and 9 pi
B) 6 sigma and 8 pi
C) 9 sigma and 7 pi
D) 9 sigma and 9 pi
E) 5 sigma and 8 pi
ANS: D PTS: 1 DIF: moderate TOP: 14.1
25. How many of the atoms are sp2 hybridized?

A) 2
B) 4
C) 6
D) 8
E) 10
KEY: general chemistry | bonding | molecular geometry | the valence-shell electron-pair
repulsion model | trigonal planar arrangement
26. How many of the atoms are sp hybridized?

A) 2
B) 4
C) 6
D) 8
E) 10
KEY: general chemistry | bonding | bonding theories | the valence-shell electron-pair
repulsion model | linear arrangement
27. Which statement about N 2 is false?

A) It is a gas at room temperature.
B) The oxidation state is +3 on one N and –3 on the other.
C) It has one sigma bond and two pi bonds between the two atoms.
D) It can combine with H 2 to form NH 3 .
E) It has two pairs of nonbonding electrons.
KEY: general chemistry | bonding | covalent bonding
What is the total number of bonds in the molecule?

A) 6
B) 7
C) 8
D) 10
E) 11
KEY: general chemistry | bonding | covalent bonding | octet rule
29. Which of the following has the shortest N-O bond?

A) NO 3 –
B) NO+
C) N 2
D) NO 2 –
E) none of these
KEY: general chemistry | bonding | covalent bonding | bond length
30. Specify the hybridization of the nitrogen atom in each of the following, in order.
NO 3 – N2 NO 2 –
3
A) sp , sp, sp
B) sp2, sp, sp2
C) sp2, sp, sp3
D) sp3, sp2, sp3
E) none of these
repulsion model
31. In which of the compounds below is there more than one kind of hybridization (sp, sp2, sp3)
for carbon?
I. CH 3 CH 2 CH 2 CH 3
II. CH 3 CH = CHCH 3
III. CH 2 = CH – CH = CH 2
IV. H – C ≡ C – H
A) II and III
B) II only
C) III and IV
D) I and IV
E) III only
repulsion model
32. The CCH bond angles in ethylene, C 2 H 4 , are 120°. What is the hybridization of the
carbon orbitals?
A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
repulsion model
Indicate the hybridizations at each N and C atom in the molecule (in sequence from left to
right).
A) sp3 sp3 sp2
B) sp3 sp3 sp3
C) sp2 sp2 sp2
D) sp2 sp3 sp2
E) none of these
KEY: general chemistry | bonding | bonding theories | the valence-shell electron-pair
repulsion model
34. Complete the Lewis structure for the following molecule.
This molecule has __________ sigma bonds and __________ pi bonds.

A) 4, 5
B) 6, 3
C) 11, 5
D) 13, 2
E) 13, 3
ANS: E PTS: 1 DIF: moderate TOP: 14.1
35. Describing the bonding in C 2 H 6 requires what carbon hybridization?

A) sp
B) sp3
C) sp2
D) d2sp3
E) dsp2
KEY: general chemistry | bonding | mass and moles of substance | the valence-shell
electron-pair repulsion model
36. Consider the following Lewis structure. (Lone pairs are not drawn in.)
What are the hybridizations of the oxygen atom and of carbon atoms 1, 2, and 4,
respectively (order: O C-1 C-2 C-4)?
A) sp3 sp3 sp sp2
B) sp sp3 sp sp
2
C) sp sp sp sp2
D) sp2 sp3 sp2 sp3
E) sp sp3 sp2 sp
37. What is the hybridization of each N atom in the molecule N 2 H 4 ?

A) sp
B) sp2
C) sp3
D) dsp3
E) d2sp3
38. Which statement about the thiocyanate ion, SCN–, is true?

A) Its Lewis structure contains an unpaired electron.
B) Its shape is bent like that of H 2 O.
C) Only one correct resonance structure can be drawn.
D) There are more than two σ bonds in the ion.
E) none of these
KEY: general chemistry | bonding
39. Which of the following statements is correct?

A) A triple bond is composed of two σ bonds and one π bond.
B) σ bonds result from the head-to-head overlap of atomic orbitals.
C) Free rotation may occur about a double bond.
D) π bonds have electron density on the internuclear axis.
E) More than one of these statements are correct.
ANS: B PTS: 1 DIF: easy TOP: 14.1 | 14.3
40. As the bond order of a bond increases, its bond energy ______ and its bond length ______.
A) increases, increases
B) decreases, decreases
C) increases, decreases
D) decreases, increases
ANS: C PTS: 1 DIF: easy TOP: 14.2 | 14.3
KEY: general chemistry | bonding | bonding theories | molecular orbital theory | bond order
41. If four orbitals on one atom overlap four orbitals on a second atom, how many molecular
orbitals will form?
A) 1
B) 4
C) 8
D) 16
E) none of these
KEY: general chemistry | bonding | bonding theories | molecular orbital theory
42. For which of the following diatomic molecules would the bond order become greater if an
electron were removed, that is, if the molecule were converted to the positive ion in its
ground state?
A) B 2
B) C 2
C) P 2
D) F 2
E) Na 2
43. The configuration (σ 2s )2(σ 2s *)2(π 2py )1(π 2px )1 is the molecular orbital description for the
ground state of which of the following species?
A) Li 2 +
B) Be 2
C) B 2
D) B 2 2–
E) C 2
44. Which of the following species has the largest dissociation energy?
A) O 2
B) O 2 –
C) O 2 2–
D) O 2 +
E) O 2 2+
45. Which of the following is diamagnetic?

A) N 2
B) C 2 +
C) H 2 +
D) N 2 +
E) F 2 +
KEY: general chemistry | bonding | bonding theories | diatomic molecule
46. Order the following from shortest to longest bond: C 2 , B 2 , H 2 , N 2

A) H2, N2, C2, B2
B) N2, C2, B2, H2
C) C2, N2, H2, B2
D) C2, B2, H2, N2
E) none of these
KEY: general chemistry | bonding | covalent bonding | bond length
47. Which charge(s) of N2 would give a bond order of 2?

A) –1
B) +2
C) –2
D) +1
E) +3
48. Which of the following statements is false?

A) C2 is paramagnetic.
B) C2 is diamagnetic.
C) The carbon-carbon bond in C22– is stronger than the one in CH3CH3.
D) The carbon-carbon bond in C22– is shorter than the one in CH3CH3.
E) Two of these statements are false.
49. Which of the following statements is true?

A) Electrons are never found in an antibonding MO.
B) All antibonding MOs are higher in energy than the atomic orbitals of which they
are composed.
C) Antibonding MOs have electron density mainly outside the space between the two
nuclei.
D) None of these statements is true.
E) Two of these statements are true.
KEY: general chemistry | bonding | bonding theories | molecular orbital theory |
antibonding orbital
50. Which of the following is paramagnetic?

A) O2–
B) O2+
C) O2
D) N2
E) At least two of these are paramagnetic.
51. Which of the following is diamagnetic?

A) O2–
B) O2+
C) B2
D) F2
E) BO
52. For how many of B2, C2, P2, and F2 does bond order decrease if one electron is removed
from the neutral molecule?
A) 0
B) 1
C) 2
D) 3
E) 4
53. Which of the following statements is false?

A) Atoms or molecules with an even number of electrons are diamagnetic.
B) Atoms or molecules with an odd number of electrons are paramagnetic.
C) Paramagnetism cannot be deduced from the Lewis structure of a molecule alone.
D) Paramagnetic molecules are attracted toward a magnetic field.
E) N2 molecules are diamagnetic.
54. For how many of the following does the bond order decrease if you add one electron to the
neutral molecule?
Be2, Si2, H2, O2
A) 0
B) 1
C) 2
D) 3
E) 4
KEY: general chemistry | bonding | bonding theories | molecular formula | bond order
55. Which of the following species is paramagnetic?

A) C2
B) B2
C) N2
D) H2
E) none of these
56. The fact that O2 is paramagnetic can be explained by

A) the Lewis structure of O2.
B) resonance.
C) a violation of the octet rule.
D) the molecular-orbital diagram for O2.
E) hybridization of atomic orbitals in O2.
57. The molecular-orbital electron configuration below

(σls)2 (σls*)2 (σ2s)2 (σ2s*)2 (π2p)4 (σ2p)2
applies to which of the following molecules?
A) F2
B) O2
C) BC
D) NO
E) CO
58. Which of the following electron distributions among the molecular orbitals best describes
the NO molecule?
σ2s σ2s* π2py = π2px σ2pz π2py* = π2px* σ2pz*
I. 2 2 4 2 4 2
II. 2 2 4 2 4 1
III. 2 2 4 1 3 0
IV. 2 2 4 2 2 0
V. 2 2 4 2 1 0
A) I
B) II
C) III
D) IV
E) V
59. Consider the molecular-orbital energy-level diagrams for O2 and NO. Which of the
following is true?
I. Both molecules are paramagnetic.
II. The bond strength of O2 is greater than the bond strength of NO.
III. NO is an example of a homonuclear diatomic molecule.
IV. The ionization energy of NO is smaller than the ionization energy of NO+.
A) I only
B) I and II only
C) I and IV
D) II and III
E) I, II, and IV
60. In the molecular-orbital description of CO,

A) the highest energy electrons occupy antibonding orbitals.
B) six molecular orbitals contain electrons.
C) there are two unpaired electrons.
D) the bond order is 3.
E) All of these are false.
61. Consider the molecular-orbital description of the NO– anion. Which of the following
statements is false?
A) NO– is paramagnetic.
B) NO– is isoelectronic with CO.
C) The bond energy in NO+ is greater than the bond energy in NO–.
D) The bond order in NO– is 2.
E) All of these statements are false.
62. The bond order in the NO– ion is

A) 1
B) 1.5
C) 3
D) 2
E) 2.5
63. How many electrons are involved in pi bonding in benzene, C6H6?

A) 12
B) 30
C) 3
D) 6
E) 18
64. Which of the following statements about the CO32– ion is false?
A) The orbitals on the carbon atom are sp2 hybridized.
B) The ion is expected to be diamagnetic.
C) One C–O bond is shorter than the others.
D) The ion has a total of 24 electrons.
E) It has a planar molecular geometry.
KEY: general chemistry | bonding | bonding theories
65. The majority of electron transitions in molecules occur in the _________ region of the
electromagnetic spectrum.
A) UV
B) IR
C) microwave
D) visible
E) X-ray
66. Vibrational transitions in molecules typically require energies that correspond to the
_________ region of the electromagnetic spectrum.
A) UV
B) IR
C) microwave
D) visible
E) X-ray
KEY: general chemistry | instrumental methods | infrared spectroscopy
67. Typically, rotational changes are produced by radiation in the _________ region of the
electromagnetic spectrum.
A) UV
B) IR
C) microwave
D) visible
E) X-ray
KEY: general chemistry | instrumental methods
68. An ethyl group (CH3CH2–) that is attached to a substituent that does not contain a hydrogen
atom appears as what in a NMR spectrum?
A) a doublet and a triplet with relative intensities of 2 and 3, respectively
B) a doublet and a triplet with relative intensities of 3 and 2, respectively
C) a triplet and a quartet with relative intensities of 2 and 3, respectively
D) a triplet and a quartet with relative intensities of 3 and 2, respectively
E) none of these
KEY: general chemistry | instrumental methods | nuclear magnetic resonance (MNR)
69. Draw a molecular-orbital diagram for O2 and N2. Using molecular-orbital theory, explain
why the removal of one electron in O2 strengthens bonding, whereas the removal of one
electron in N2 weakens bonding.
ANS:
See Section 14.3 of Zumdahl, Chemical Principles.
PTS: 1 DIF: moderate TOP: 14.3

70. Determine which of the following atoms is(are) paramagnetic in the ground state, and
arrange the atoms in order of increasing paramagnetism.
N O Ne Ca Al Zn
ANS:
N, O, and Al are paramagnetic. The order of increasing paramagnetism is Al, O, N.
PTS: 1 DIF: moderate TOP: 14.3

KEY: general chemistry | atomic theory | electronic structure of atoms | electron
configurations of ions | magnetic properties of atoms
71. Give the bond order for each of the following:

a) H2
b) H2+
c) H2–
d) CN–
e) CN
f) CN+
ANS:
a) 1
b) 0.5
c) 0.5
d) 3
e) 2.5
f) 2
PTS: 1 DIF: moderate TOP: 14.3 | 14.4

KEY: general chemistry | bonding | bonding theories | molecular formula | bond order
72. Which of the following are paramagnetic?

O2 O2– O22– B2 C2 N2 F2 CN– P2
ANS:
O2 , O2– ,B2
PTS: 1 DIF: moderate TOP: 14.3 | 14.4

73. Of the following homonuclear diatomic molecules, which is paramagnetic?

A) B2
B) C2
C) N2
D) F2
E) None of the above
ANS: A PTS: 1
74. Oxygen is paramagnetic and has a bond order of two. Which of the following represents the ground
electronic state for oxygen?
A)
B)
C)
D) A and C are equally probable

E) None of the above
ANS: A PTS: 1
75. An electron is promoted from the p to the p* molecular orbital in an N2 molecule following the
absorption of a photon. Compared to the bond length in the non-excited molecule, the N2 bond
length will
A) be shorter
B) be longer
C) not be affected
ANS: B PTS: 1
76. According to MO theory, which molecule(s) do not exist?
A) H
B) H
C) H
D) H
E) A, B, and D
ANS: A PTS: 1

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Chapter 14: Covalent Bonding: Orbitals

2. Consider the structure of glycine, the simplest amino acid:

What is the total number of π bonds in the molecule?

3. What is the hybridization of I in the molecule IF 3 ?

4. What is the hybridization of S in the molecule H 2 S?

5. What is the hybridization of C in the ion CN–?

6. Atoms that are sp3 hybridized form ____ pi bond(s).

7. What is the hybridization of the central atom in SF 6 ?

8. What is the hybridization of the central atom in PCl 4 +?

9. What is the hybridization of the central atom in ICl 5 ?

10. What is the hybridization of the central atom in SF 4 ?

11. What is the hybridization of I in ICl 2 +?

13. What is the hybridization of the phosphorus atom in PCl 4 +?

16. What is the hybridization of the B atom in the molecule BF 3 ?

17. What is the hybridization of the I atom in the molecule IF 5 ?

20. What is the hybridization of the nitrogen atom?

21. What is the hybridization of the oxygen atom?

22. Which of the following has two π bonds?

Which statement about the molecule is false?

From its Lewis structure, determine the following.

25. How many of the atoms are sp2 hybridized?

26. How many of the atoms are sp hybridized?

27. Which statement about N 2 is false?

28. Consider the structure of glycine, the simplest amino acid:

What is the total number of bonds in the molecule?

29. Which of the following has the shortest N-O bond?

33. Consider the structure of glycine, the simplest amino acid:

34. Complete the Lewis structure for the following molecule.

This molecule has __________ sigma bonds and __________ pi bonds.

35. Describing the bonding in C 2 H 6 requires what carbon hybridization?

37. What is the hybridization of each N atom in the molecule N 2 H 4 ?

38. Which statement about the thiocyanate ion, SCN–, is true?

39. Which of the following statements is correct?

45. Which of the following is diamagnetic?

46. Order the following from shortest to longest bond: C 2 , B 2 , H 2 , N 2

47. Which charge(s) of N2 would give a bond order of 2?

48. Which of the following statements is false?

49. Which of the following statements is true?

50. Which of the following is paramagnetic?

51. Which of the following is diamagnetic?

53. Which of the following statements is false?

55. Which of the following species is paramagnetic?

56. The fact that O2 is paramagnetic can be explained by

57. The molecular-orbital electron configuration below

60. In the molecular-orbital description of CO,

62. The bond order in the NO– ion is

63. How many electrons are involved in pi bonding in benzene, C6H6?

PTS: 1 DIF: moderate TOP: 14.3

PTS: 1 DIF: moderate TOP: 14.3

71. Give the bond order for each of the following:

PTS: 1 DIF: moderate TOP: 14.3 | 14.4

72. Which of the following are paramagnetic?

PTS: 1 DIF: moderate TOP: 14.3 | 14.4

73. Of the following homonuclear diatomic molecules, which is paramagnetic?

D) A and C are equally probable

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