Deck 11: Theories of Covalent Bonding

Question 1

Valence bond theory predicts that tin will use _____ hybrid orbitals in SnCl₃^-.

A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²

Answer 1

sp³

Question 2

According to valence bond theory, which of the following molecules involves sp² hybridization of orbitals on the central atom? (central atom is bold)

A) C₂H₂
B) C₂H₄
C) C₂H₆
D) CO₂
E) H₂O

Answer 2

C₂H₄

Question 3

Carbon uses ______ hybrid orbitals in ClCN.

A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²

Answer 3

sp

Question 4

Valence bond theory predicts that sulfur will use _____ hybrid orbitals in sulfur dioxide, SO₂.

A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²

Question 5

Valence bond theory predicts that tin will use _____ hybrid orbitals in SnF₅^-.

A) sp²
B) sp³
C) sp³d
D) sp³d ²
E) d²sp³

Question 6

Valence bond theory predicts that xenon will use _____ hybrid orbitals in XeOF₄.

A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²

Question 7

Valence bond theory predicts that carbon will use _____ hybrid orbitals in the carbonate anion, CO₃^2-.

A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²

Question 8

For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom?

A) BeCl₂ sp²
B) SiH₄ sp³
C) BF₃ sp²
D) C₂H₂ sp
E) H₂O sp³

Question 9

A molecule with the formula AX₄E₂ uses _________ to form its bonds.

A) sp hybrid orbitals
B) sp² hybrid orbitals
C) sp³ hybrid orbitals
D) sp³d hybrid orbitals
E) sp³d² hybrid orbitals

Question 10

According to valence bond theory, which orbitals on N and H overlap in the NH₃ molecule?

A) 2p on N overlaps with 2s on H
B) 2p on N overlaps with 1s on H
C) 2s on N overlaps with 1s on H
D) sp³ on N overlaps with sp on H
E) sp³ on N overlaps with 1s on H

Question 11

When PCl₅ solidifies it forms PCl₄⁺ cations and PCl₆^- anions. According to valence bond theory, what hybrid orbitals are used by phosphorus in the PCl₄⁺ cations?

A) sp
B) sp²
C) sp³
D) sp³d
E) sp³d²

Question 12

Valence bond theory predicts that bromine will use _____ hybrid orbitals in BrF₅.

A) sp²
B) sp³
C) sp³d
D) sp³d ²
E) none of the above

Question 13

Valence bond theory predicts that bromine will use _____ hybrid orbitals in BrF₃.

A) sp²
B) sp³
C) sp³d
D) sp⁴
E) sp³d²

Question 14

Which one of the following statements about orbital hybridization is incorrect?

A) The carbon atom in CH₄ is sp³ hybridized.
B) The carbon atom in CO₂ is sp hybridized.
C) The nitrogen atom in NH₃ is sp² hybridized.
D) sp² hybrid orbitals are coplanar, and at 120° to each other.
E) sp hybrid orbitals lie at 180° to each other.

Question 15

A molecule with the formula AX₂ uses _________ to form its bonds.

A) sp hybrid orbitals
B) sp² hybrid orbitals
C) sp³ hybrid orbitals
D) sp³d hybrid orbitals
E) sp³d² hybrid orbitals

Question 16

A molecule with the formula AX₃E uses _________ to form its bonds.

A) s and p atomic orbitals
B) sp³ hybrid orbitals
C) sp² hybrid orbitals
D) sp hybrid orbitals
E) sp³d² hybrid orbitals

Question 17

A molecule with the formula AX₄ uses _________ to form its bonds.

A) sp hybrid orbitals
B) sp² hybrid orbitals
C) sp³ hybrid orbitals
D) sp³d hybrid orbitals
E) sp³d² hybrid orbitals

Question 18

A molecule with the formula AX₃ uses __________ to form its bonds.

A) sp hybrid orbitals
B) sp² hybrid orbitals
C) sp³ hybrid orbitals
D) sp³d hybrid orbitals
E) sp³d² hybrid orbitals

Question 19

A molecule with the formula AX₄E uses _________ to form its bonds.

A) sp² hybrid orbitals
B) sp³ hybrid orbitals
C) sp³d hybrid orbitals
D) sp³d² hybrid orbitals
E) none of the above

Question 20

Valence bond theory predicts that iodine will use _____ hybrid orbitals in ICl₂^-.

A) sp²
B) sp³
C) sp³d
D) sp³d ²
E) none of the above

Question 21

Which of the following statements relating to molecular orbital (MO) theory is incorrect?

A) Combination of two atomic orbitals produces one bonding and one antibonding MO.
B) A bonding MO is lower in energy than the two atomic orbitals from which it is formed.
C) Combination of two 2p orbitals may result in either $\sigma$ or $\pi$ MOs.
D) A species with a bond order of zero will not be stable.
E) In a stable molecule having an even number of electrons, all electrons must be paired.

Question 22

According to molecular orbital theory, what is the bond order in the O₂⁺ ion?

A) 5.5
B) 5
C) 4
D) 2.5
E) 1.5

Question 23

What type of hybridization is needed to explain why ethyne, C₂H₂, is linear?

Question 24

According to molecular orbital (MO) theory, the twelve outermost electrons in the O₂ molecule are distributed as follows:

A) 12 in bonding MOs, 0 in antibonding MOs.
B) 10 in bonding MOs, 2 in antibonding MOs.
C) 9 in bonding MOs, 3 in antibonding MOs.
D) 8 in bonding MOs, 4 in antibonding MOs.
E) 7 in bonding MOs, 5 in antibonding MOs.

Question 25

Select the correct statement about $\pi$ -bonds in valence bond theory.

A) A $\pi$ bond is stronger than a sigma bond.
B) A $\pi$ bond can hold 4 electrons, two above and two below the $\pi$ -bond axis.
C) A carbon-carbon double bond consists of two $\pi$ bonds.
D) A $\pi$ bond is the same strength as a $\sigma$ bond.
E) A $\pi$ bond between two carbon atoms restricts rotation about the C-C axis.

Question 26

One can safely assume that the 3s- and 3p-orbitals will form molecular orbitals similar to those formed when 2s- and 2p-orbitals interact. According to molecular orbital theory, what will be the bond order for the Cl₂⁺ ion?

A) 0.5
B) 1
C) 1.5
D) 2
E) none of the above

Question 27

In one sentence state how molecular orbitals are usually obtained.

Question 28

Which one, if any, of the following statements about the MO treatment of the bonding in benzene is correct?

A) MO theory uses resonance to describe the delocalized nature of the bonding in benzene.
B) The lowest energy pi-bonding orbital in benzene can hold up to 6 electrons.
C) MO theory predicts that benzene should be paramagnetic.
D) The lowest energy pi-bonding MO in benzene has two hexagonal lobes, above and below the plane of the carbon atoms.
E) None of the above statements is correct.

Question 29

In one sentence state the basic principle of valence bond theory.

Question 30

According to the molecular orbital (MO) treatment of the NO molecule, what are the bond order and the number of unpaired electrons, respectively?

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

Question 31

Describe the bonding in ethylene (ethene, C₂H₄) according to valence bond theory. Be sure to indicate the orbital hybridization on the carbon atoms. Draw a diagram clearly showing at least one bond of each type which occurs in the molecule.

Question 32

According to valence bond theory, the triple bond in ethyne (acetylene, C₂H₂) consists of

A) three $\sigma$ bonds and no $\pi$ bonds.
B) two $\sigma$ bonds and one $\pi$ bond.
C) one $\sigma$ bond and two $\pi$ bonds.
D) no $\sigma$ bonds and three $\pi$ bonds.
E) none of the above.

Question 33

In the context of molecular orbital (MO) theory, explain how atomic p orbitals can give rise to:
a. a $\sigma$ MO
b. a $\pi$ MO

Question 34

Determine the shape (geometry) of PCl₃ and then decide on the appropriate hybridization of phosphorus in this molecule. (Phosphorus is the central atom.)

A) sp³
B) sp²
C) sp
D) sp³d
E) sp³d ²

Question 35

The nitrosonium ion, NO⁺, forms a number of interesting complexes with nickel, cobalt, and iron. According to molecular orbital theory, which of the following statements about NO⁺ is correct?

A) NO⁺ has a bond order of 2 and is paramagnetic.
B) NO⁺ has a bond order of 2 and is diamagnetic.
C) NO⁺ has a bond order of 3 and is paramagnetic.
D) NO⁺ has a bond order of 3 and is diamagnetic.
E) None of the above statements is correct.

Question 36

a. In the context of valence bond theory, explain the difference in geometry between a $\sigma$ and a $\pi$ bond. Use a real molecule to illustrate your answer.
b. What two important differences are there in the properties of $\sigma$ and $\pi$ bonds, in terms of how they affect the structure and reactivity of molecules?

Question 37

Explain what is meant by a node (or nodal plane) in a molecular orbital and draw sketches of the following orbitals, indicating at least one nodal plane in each one.
a. a $\sigma$ * orbital
b. a $\pi$ * orbital

Question 38

How many sigma and pi bonds, respectively, are in the molecule below? CH₃CH₂CHCHCH₃?

A) 16, 1
B) 16, 0
C) 15, 1
D) 15, 0
E) 14, 1

Question 39

Sketch the shapes of the $\sigma$ _1s and $\sigma$ _1s* molecular orbitals formed by the overlap of two hydrogen 1s atomic orbitals.

Question 40

In not more than two sentences, explain when and why chemists make use of the concept of hybridization.

Question 41

a. What simple experiment could you perform to show that a substance is paramagnetic?
b. What microscopic (atomic/molecular) feature must a substance possess in order to be paramagnetic?
c. Can it be predicted whether or not all homonuclear diatomic ions, X₂⁺, will be paramagnetic? Explain.

Question 42

According to valence bond theory, overlap of bonding orbitals of atoms will weaken a bond, due to electron-electron repulsion.

Question 43

Valence bond theory explains the bonding in diatomic molecules such as HCl without resorting to the use of hybrid orbitals.

Question 44

In molecular orbital theory, combination of two atomic orbitals produces two molecular orbitals.

Question 45

Valence bond theory is able to explain why molecular oxygen is paramagnetic.

Question 46

According to molecular orbital theory, all diatomic molecules with an even number of electrons will be diamagnetic.

Question 47

Atoms of period 3 and beyond can undergo sp³d ² hybridization, but atoms of period 2 cannot.

Question 48

In the valence bond treatment, a $\pi$ bond is formed when two 2p orbitals overlap side to side.

Question 49

In molecular orbital theory, combination of two 2p atomic orbitals may give rise to either $\sigma$ or $\pi$ type molecular orbitals.

Question 50

A carbon-carbon double bond in a molecule may give rise to the existence of cis and trans isomers.

Question 51

A carbon-carbon triple bond in a molecule may give rise to the existence of cis and trans isomers.

Question 52

In the valence bond treatment, overlap of an s orbital on one atom with an sp³ orbital on another atom can give rise to a $\sigma$ bond.

Question 53

Hybrid orbitals of the sp³d type occur in sets of four.

Question 54

In molecular orbital theory, molecules with an even number of electrons will have bond orders which are whole numbers.

Question 55

Explain what is meant by the term "bond order" and describe how it can be calculated using the information in a molecular orbital energy level diagram.

Question 56

In applying molecular orbital theory, the bond order is calculated in the same way as with Lewis structures.

Question 57

The angles between sp² hybrid orbitals are 109.5°.

Question 58

Overlap of two sp² hybrid orbitals produces a $\pi$ bond.