Question 1

Which of the following statements best explains why O$$_2 is $$paramagnetic according to molecular orbital theory?

Accepted Answer

Because O$$_2$$ has two unpaired electrons in its antibonding $$\pi^*$$ molecular orbitals.

Question 2

Calculate the bond order for the molecule He$$_2^+$$ using molecular orbital theory.

Accepted Answer

$$\frac{1}{2}$$

Question 3

Which of the following diatomic molecules or ions is predicted to be stable according to molecular orbital theory?

Accepted Answer

Li$$_2$$

Question 4

For the molecule N$$_2$$, what is the bond order and what does this imply about its bond strength compared to O$$_2$$?

Accepted Answer

Bond order is 3; N$$_2$$ has a stronger bond than O$$_2.$$

Question 5

Which of the following best describes the difference between a $$\sigma$$ and a $$\pi$$ molecular orbital?

Accepted Answer

A $$\sigma MO $$results from end-to-end overlap along the internuclear axis, while a $$\pi MO $$results from sideways overlap above and below the axis.

Question 6

Given the molecular orbital configuration for F$$_2$$: $$(\sigma_{2s})^2$ (\sigma^*_{2s})^2$ (\sigma_{2p})^2$ (\pi_{2p_y})^2$ (\pi_{2p_z})^2$ (\pi^*_{2p_y})^2$ (\pi^*_{2p_z})^2$, what is the bond order?

Accepted Answer

1

Question 7

Which of the following molecules is predicted to be paramagnetic according to molecular orbital theory?

Accepted Answer

B$$_2$$

Question 8

A student claims that He$$_2$$ should exist because each He atom can form a bond with the other. Using molecular orbital theory, explain why this is incorrect.

Accepted Answer

He$$_2$$ has a bond order of 0, so it is not stable and does not exist.

Question 9

Which of the following correctly describes the electron configuration for the O$$_2$$ molecule using molecular orbital theory?

Accepted Answer

$$(\sigma_{2s})^2$ (\sigma^*_{2s})^2$ (\sigma_{2p})^2$ (\pi_{2p_y})^2$ (\pi_{2p_z})^2$ (\pi^*_{2p_y})^1$ (\pi^*_{2p_z})^1$

Question 10

Which of the following ions is predicted to be more stable than its neutral molecule counterpart, based on bond order calculations?

Accepted Answer

O$$_2^+$$

Question 11

A molecule has the following electron configuration: $$(\sigma_{1s})^2$ (\sigma^*_{1s})^2$ (\sigma_{2s})^2$ (\sigma^*_{2s})^2$ (\pi_{2p_y})^1$ (\pi_{2p_z})^1$. What is the bond order and is the molecule paramagnetic or diamagnetic?

Accepted Answer

Bond order = 1; paramagnetic

Question 12

Which of the following best explains why the bond order of Ne$$_2 is $$zero?

Accepted Answer

The number of electrons in bonding and antibonding molecular orbitals is equal, resulting in no net bond.

Question 13

Which of the following is true about the energy of bonding and antibonding molecular orbitals?

Accepted Answer

Bonding MOs are lower in energy than the atomic orbitals from which they are formed; antibonding MOs are higher in energy.

Question 14

A patient is exposed to a gas that is paramagnetic and has a double bond. Which of the following is most likely the gas?

Accepted Answer

O$$_2$$

Question 15

Which of the following statements about the filling of molecular orbitals is correct?

Accepted Answer

Electrons fill molecular orbitals from lowest to highest energy, and degenerate orbitals are filled singly before pairing, following Hund's rule.

Question 16

Which of the following best describes the bond order and magnetic properties of C$$_2$$?

Accepted Answer

Bond order = 2; diamagnetic

Question 17

If a molecule has a bond order of zero, what does this indicate about its stability?

Accepted Answer

The molecule is not stable and does not exist under normal conditions.

Question 18

Which of the following is the correct order of molecular orbital energies for O$$_2$$?

Accepted Answer

$$\sigma_{2s} \u003c \sigma^*_{2s} \u003c \sigma_{2p} \u003c \pi_{2p_y} = \pi_{2p_z} \u003c \pi^*_{2p_y} = \pi^*_{2p_z} \u003c \sigma^*_{2p}$$

Question 19

A researcher is studying a new diatomic molecule with 14 electrons. According to molecular orbital theory, what is the bond order and magnetic property of this molecule?

Accepted Answer

Bond order = 3; diamagnetic

chapter 8 part 2

Study Guide - Practice Questions

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