Deck 14: Covalent Bonding: Orbitals

Question 1

Consider the following molecule. (Lone pairs are not drawn in.)
What is the hybridization of the carbon atom that is bonded to chlorine?

A) dsp³
B) sp³
C) sp
D) sp²
E) d²sp³

Answer 1

sp³

Question 2

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

A) 1
B) 4
C) 2
D) 3
E) 0

Answer 2

0

Question 3

Consider the structure of glycine, the simplest amino acid: What is the total number of $\pi$ bonds in the molecule?

A) 0
B) 1
C) 2
D) 1/2
E) More information is needed.

Answer 3

1

Question 4

What is the hybridization of the central I atom in the molecule ICl₅?

A) sp
B) sp²
C) dsp³
D) sp³
E) d²sp³

Question 5

Consider the following molecule. (Lone pairs are not drawn in.)
What is the hybridization of the nitrogen atom?

A) sp²
B) d²sp³
C) sp
D) sp³
E) dsp³

Question 6

Which of the following molecules contains a nitrogen atom that is sp² hybridized?

A) NO₂^-
B) NCl₃
C) C₂N₂
D) N₂
E) HCN

Question 7

What is the hybridization of I in ICl₂⁺?

A) sp³
B) dsp³
C) sp²
D) sp
E) d²sp³

Question 8

Which of the following has a central atom that is dsp³ hybridized?

A) SO₃
B) SBr₆
C) CBr₄
D) SF₄
E) SCl₄^-

Question 9

What is the hybridization of the central atom in SF₄?

A) dsp³
B) sp³
C) d²sp³
D) sp
E) sp²

Question 10

What is the hybridization of S in the molecule H₂S?

A) d²sp³
B) dsp³
C) sp²
D) sp³
E) sp

Question 11

What is the hybridization of C in the ion CN^-?

A) dsp³
B) sp²
C) d²sp³
D) sp
E) sp³

Question 12

What is the hybridization of the phosphorus atom in PCl₄⁺?

A) dsp²
B) sp²d
C) d²sp³
D) sp²
E) sp³

Question 13

What is the hybridization of the central atom in ICl₅?

A) sp²
B) d²sp³
C) dsp³
D) sp
E) sp³

Question 14

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 ssp² sp³ sp³ sp³
B) sp² sp² sp³ sp³ sp
C) sp sp sp sp² sp
D) sp² sp² sp² sp³ sp³
E) sp² sp² sp² sp³ sp

Question 15

Consider the following molecule. (Lone pairs are not drawn in.)
What is the hybridization of the carbon atom that is double-bonded to oxygen?

A) sp³
B) sp²
C) dsp³
D) sp
E) d²sp³

Question 16

What is the hybridization of the central atom in PCl₄⁺?

A) sp³
B) sp
C) dsp³
D) d²sp³
E) sp²

Question 17

What is the hybridization of the B atom in the molecule BF₃?

A) sp²
B) d²sp³
C) sp
D) sp³
E) dsp³

Question 18

What is the hybridization of I in the molecule IF₃?

A) sp³
B) sp²
C) d²sp³
D) dsp³
E) sp

Question 19

What is the hybridization of the central atom in SF₆?

A) sp²
B) d²sp³
C) dsp³
D) sp
E) sp³

Question 20

What is the hybridization of the I atom in the molecule IF₅?

A) sp
B) sp³
C) dsp³
D) sp²
E) d²sp³

Question 21

Which statement about N₂ is false?

A) It is a gas at room temperature.
B) It can combine with H₂ to form NH₃.
C) It has two pairs of nonbonding electrons.
D) It has one sigma bond and two pi bonds between the two atoms.
E) The oxidation state is +3 on one N and -3 on the other.

Question 22

Consider the structure of glycine, the simplest amino acid: Indicate the hybridizations at each N and C atom in the molecule (in sequence from left to right).

A) sp³ sp³ sp²
B) sp² sp² sp²
C) sp³ sp³ sp³
D) sp² sp³ sp²
E) none of these

Question 23

Which statement about the thiocyanate ion, SCN^-, is true?

A) Only one correct resonance structure can be drawn.
B) Its Lewis structure contains an unpaired electron.
C) Its shape is bent like that of H₂O.
D) There are more than two $\sigma$ bonds in the ion.
E) none of these

Question 24

The C-C-H bond angles in ethylene, C₂H₄, are 120 $\degree$ . What is the hybridization of the carbon orbitals?

A) sp
B) d²sp³
C) dsp³
D) sp³
E) sp²

Question 25

Complete the Lewis structure for the following molecule. This molecule has __________ sigma bonds and __________ pi bonds.

A) 11, 5
B) 13, 3
C) 4, 5
D) 13, 2
E) 6, 3

Question 26

Describing the bonding in C₂H₆ requires what carbon hybridization?

A) sp
B) sp³
C) dsp²
D) d²sp³
E) sp²

Question 27

Tetracyanoethylene has the skeleton shown here: From its Lewis structure, determine the following.
How many of the atoms are sp hybridized?

A) 10
B) 2
C) 8
D) 6
E) 4

Question 28

In which of the compounds below is there more than one kind of hybridization (sp, sp², sp³) for carbon? I. CH₃CH₂CH₂CH₃
II) CH₃CH = CHCH₃
III) CH₂ = CH - CH = CH₂
IV) H - C $\equiv$ C - H

A) III and IV
B) II only
C) II and III
D) I and IV
E) III only

Question 29

As the bond order of a bond increases, its bond energy ______ and its bond length ______.

A) decreases, increases
B) increases, increases
C) increases, decreases
D) decreases, decreases

Question 30

Which of the following statements is correct?

A) ( $\sigma$ bonds result from the head-to-head overlap of atomic orbitals).
B) A triple bond is composed of two $\sigma$ bonds and one $\pi$ bond.
C) Free rotation may occur about a double bond.
D) ( $\pi$ bonds have electron density on the internuclear axis).
E) More than one of these statements are correct.

Question 31

Consider the following Lewis structure. (Lone pairs are not drawn in.) Which statement about the molecule is false?

A) Oxygen is sp³ hybridized.
B) This molecule contains 28 valence electrons.
C) C-2 is sp² hybridized with bond angles of 120.
D) There are 10 sigma and 2 pi bonds.
E) There are some H-C-H bond angles of about 109 $\degree$ in the molecule.

Question 32

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

A) NO₂^-
B) N₂
C) NO⁺
D) NO₃^-
E) none of these

Question 33

What is the hybridization of each N atom in the molecule N₂H₄?

A) sp²
B) sp
C) sp³
D) d²sp³
E) dsp³

Question 34

Consider the structure of glycine, the simplest amino acid: What is the total number of bonds in the molecule?

A) 10
B) 11
C) 7
D) 6
E) 8

Question 35

Tetracyanoethylene has the skeleton shown here: From its Lewis structure, determine the following.
How many of the atoms are sp² hybridized?

A) 2
B) 4
C) 10
D) 8
E) 6

Question 36

Consider the following molecule. (Lone pairs are not drawn in.)
What is the hybridization of the oxygen atom?

A) sp
B) dsp³
C) sp³
D) sp²
E) d²sp³

Question 37

Specify the hybridization of the nitrogen atom in each of the following, in order. NO₃^- N₂ NO₂^-

A) sp², sp, sp²
B) sp³, sp, sp
C) sp², sp, sp³
D) sp³, sp², sp³
E) none of these

Question 38

Which of the following has two $\pi$ bonds?

A) C₂H₆
B) C₂H₂
C) C₂H₄
D) at least two of these
E) none of these

Question 39

Tetracyanoethylene has the skeleton shown here: From its Lewis structure, determine the following.
How many sigma bonds and how many pi bonds are in the molecule?

A) 9 sigma and 9 pi
B) 9 sigma and 7 pi
C) 5 sigma and 8 pi
D) 6 sigma and 8 pi
E) 5 sigma and 9 pi

Question 40

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) sp² sp³ sp² sp³
B) sp sp³ sp sp
C) sp³ sp³ sp sp²
D) sp sp² sp sp²
E) sp sp³ sp² sp

Question 41

Which of the following species is paramagnetic?

A) N₂
B) H₂
C) C₂
D) B₂
E) none of these

Question 42

Which of the following is diamagnetic?

A) O₂^-
B) B₂
C) BO
D) O₂⁺
E) F₂

Question 43

The fact that O₂ is paramagnetic can be explained by

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

Question 44

Order the following from shortest to longest bond: C₂, B₂, H₂, N₂

A) H₂, N₂, C₂, B₂
B) C₂, N₂, H₂, B₂
C) N₂, C₂, B₂, H₂
D) C₂, B₂, H₂, N₂
E) none of these

Question 45

Which of the following statements is false?

A) The carbon-carbon bond in C₂^2- is shorter than the one in CH₃CH₃.
B) The carbon-carbon bond in C₂^2- is stronger than the one in CH₃CH₃.
C) C₂ is diamagnetic.
D) C₂ is paramagnetic.
E) Two of these statements are false.

Question 46

Which of the following is diamagnetic?

A) F₂⁺
B) C₂⁺
C) H₂⁺
D) N₂
E) N₂⁺

Question 47

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) 2
B) 1
C) 3
D) 0
E) 4

Question 48

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

A) -1
B) +1
C) +2
D) -2
E) +3

Question 49

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 and II only
B) I, II, and IV
C) I and IV
D) II and III
E) I only

Question 50

The molecular-orbital electron configuration below ( $\sigma$ _ls)² ( $\sigma$ _ls*)² ( $\sigma$ _2s)² ( $\sigma$ _2s*)² ( $\pi$ _2p)⁴ ( $\sigma$ _2p)²
Applies to which of the following molecules?

A) NO
B) BC
C) F₂
D) O₂
E) CO

Question 51

Which of the following species has the largest dissociation energy?

A) O₂⁺
B) O₂^-
C) O₂²⁺
D) O₂
E) O₂^2-

Question 52

Which of the following is paramagnetic?

A) N₂
B) O₂
C) O₂^-
D) O₂⁺
E) At least two of these are paramagnetic.

Question 53

Which of the following statements is true?

A) All antibonding MOs are higher in energy than the atomic orbitals of which they are composed.
B) Electrons are never found in an antibonding MO.
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.

Question 54

Which of the following electron distributions among the molecular orbitals best describes the NO molecule?

A) IV
B) V
C) III
D) I
E) II

Question 55

In the molecular-orbital description of CO,

A) the bond order is 3.
B) six molecular orbitals contain electrons.
C) there are two unpaired electrons.
D) the highest energy electrons occupy antibonding orbitals.
E) All of these are false.

Question 56

If four orbitals on one atom overlap four orbitals on a second atom, how many molecular orbitals will form?

A) 1
B) 8
C) 4
D) 16
E) none of these

Question 57

Which of the following statements is false?

A) Paramagnetic molecules are attracted toward a magnetic field.
B) Paramagnetism cannot be deduced from the Lewis structure of a molecule alone.
C) Atoms or molecules with an even number of electrons are diamagnetic.
D) N₂ molecules are diamagnetic.
E) Atoms or molecules with an odd number of electrons are paramagnetic.

Question 58

For how many of B₂, C₂, P₂, and F₂ does bond order decrease if one electron is removed from the neutral molecule?

A) 3
B) 4
C) 1
D) 2
E) 0

Question 59

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) F₂
B) Na₂
C) P₂
D) B₂
E) C₂

Question 60

The configuration ( $\sigma$ _2s)²( $\sigma$ _2s*)²( $\pi$ _2py)¹( $\pi$ _2px)¹ is the molecular orbital description for the ground state of which of the following species?

A) Be₂
B) Li₂⁺
C) B₂^2-
D) B₂
E) C₂

Question 61

An electron is promoted from the $\pi$ to the $\pi$ ^* 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) not be affected
B) belonger
C) be shorter

Question 62

Which of the following statements about the CO₃^2- ion is false?

A) The ion has a total of 24 electrons.
B) The orbitals on the carbon atom are sp² hybridized.
C) The ion is expected to be diamagnetic.
D) One C-O bond is shorter than the others.
E) It has a planar molecular geometry.

Question 63

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

Question 64

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.

Question 65

Which of the following are paramagnetic?
O₂ O₂^- O₂^2- B₂ C₂ N₂ F₂ CN^- P₂

Question 66

Of the following homonuclear diatomic molecules, which is paramagnetic?

A) C₂
B) B₂
C) F₂
D) N₂
E) None of the above

Question 67

Vibrational transitions in molecules typically require energies that correspond to the _________ region of the electromagnetic spectrum.

A) visible
B) microwave
C) IR
D) X-ray
E) UV

Question 68

Typically, rotational changes are produced by radiation in the _________ region of the electromagnetic spectrum.

A) IR
B) UV
C) microwave
D) visible
E) X-ray

Question 69

The majority of electron transitions in molecules occur in the _________ region of the electromagnetic spectrum.

A) microwave
B) visible
C) X-ray
D) IR
E) UV

Question 70

Give the bond order for each of the following:

A) H₂
B) H₂⁺
C) H₂^-
D) CN^-
E) CN
F) CN⁺

Question 71

Consider the molecular-orbital description of the NO^- anion. Which of the following statements is false?

A) The bond energy in NO⁺ is greater than the bond energy in NO^-.
B) The bond order in NO^- is 2.
C) NO^- is isoelectronic with CO.
D) NO^- is paramagnetic.
E) All of these statements are false.

Question 72

The bond order in the NO^- ion is

A) 2.5
B) 3
C) 2
D) 1
E) 1.5

Question 73

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

Question 74

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

A) 18
B) 6
C) 30
D) 3
E) 12

Question 75

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 triplet and a quartet with relative intensities of 3 and 2, respectively
B) a triplet and a quartet with relative intensities of 2 and 3, respectively
C) a doublet and a triplet with relative intensities of 2 and 3, respectively
D) a doublet and a triplet with relative intensities of 3 and 2, respectively
E) none of these

Question 76

According to MO theory, which molecule(s) do not exist?

A) H
B) H
C) H
D) H
E) A, B, and D