Chapter 10 Homework

Question 1

Sulfur trioxide, SO3, reacts with water to yield sulfuric acid. Sulfur trioxide has the following three resonance structures and others (not shown) in which the octet is expanded. Which of the following statements best describes the SN for the sulfur atom in SO3?

Answer 1

The SN in all three structures is the same. It is equal to 3.

Question 2

Which statement about steric number is true?

Answer 2

The steric number is equal to the number of bonded atoms plus the number of lone pairs around a central atom.

Question 3

In the molecule, SF2, what is the correct steric number for sulfur and what is the molecular geometry for the molecule?

Answer 3

SN = 4, bent

Question 4

Which of the following is not a molecular shape observed for molecules with central atoms having SN = 5?

Answer 4

Trigonal planar.

Question 5

Which of the following molecules does not have a tetrahedral molecular geometry?

Answer 5

XeF4

Question 6

Identify the polar molecules from the following list.

CO, NH3, XeF2, COS, CCl4

Answer 6

CO, NH3, COS

Question 7

When forming a bond in a diatomic molecule such as H2, what interaction prevents the two atoms from wanting to get very close together? That is, for H2, why is the ideal internuclear separation equal to 74 pm and not smaller?

Answer 7

The nuclear-nuclear repulsion becomes large at close distances

Question 8

What constitutes a σ bond and how is it different from a π bond?

Answer 8

a σ results from overlap of half filled orbitals that increases the electron density along the internuclear axis; in contrast, a π bond increases electron density above and below the internuclear axis.

Question 9

What is the hybridization of the bromine atom in BrF5?

Answer 9

sp^3d^2

Question 10

Consider the hydrogen cyanide molecule, HCN. If we orient this linear molecule so it is along the x axis, what orbitals on carbon are involved in the formation of the sp hybrid?

Answer 10

2s and 2px

Question 11

Examine the figure below, and determine which one of the following statements regarding the depiction of the carbon dioxide molecule is true?

Answer 11

The electron probability clouds that are depicting the sigma bonding in the molecule are illustrated.

Question 12

Based on MO theory, which of the following has the highest O–O bond order?

Answer 12

O2+

Question 13

Which of the following statements applies to antibonding molecular orbitals and not to bonding orbitals?

Answer 13

The wave functions add destructively between the two nuclei, resulting in a decrease in electron density between the nuclei.

Question 14

Which of the following chemical species has the strongest bond?

Answer 14

H2

Question 15

Look at the diagram for the valence electron assignments for O2.

Which of the following answers correctly describes the species that have one unpaired electron?

Answer 15

O2+ and O2−

Question 16

Where are the two degenerate bonding π orbitals located in the diagram?

Answer 16

3 or 4

Question 17

Which orbital formation is shown in the diagram?

Answer 17

π* bond

Question 18

Which of the following is an experimental fact that valence bond theory cannot explain, but molecular orbital theory can?

Answer 18

the paramagnetism observed for O2

Question 19

Which statement regarding the structure of benzene (shown below) is true?

Answer 19

The pi electrons are distributed over the entire molecule.

Question 20

The four p orbitals on carbon atoms can arrange themselves in four different ways, as shown in the drawing.

Which statement about the four possible bonding arrangements for the p orbitals is not correct?

Answer 20

There are no in-phase orbital interactions shown in this drawing.