$\frac{\text{number of bonding electrons} - \text{number of antibonding electrons}}{2}$

Question 1

Which of the following best explains why the Lewis structure of diatomic oxygen ($\mathrm{O_2}$) does not predict its magnetic properties?

Accepted Answer

The Lewis structure does not account for the presence of unpaired electrons in $\mathrm{O_2}$.

Question 2

Which of the following statements about the magnetic properties of $\mathrm{O_2}$ is correct?

Accepted Answer

$\mathrm{O_2}$ is paramagnetic because it has two unpaired electrons in its molecular orbitals.

Question 3

Which of the following best describes the difference between a sigma ($\sigma$) bond and a pi ($\pi$) bond?

Accepted Answer

A $\sigma$ bond results from head-on overlap of orbitals, while a $\pi$ bond results from side-by-side overlap.

Question 4

Which of the following is the correct bond order for the $\mathrm{O_2}$ molecule according to molecular orbital theory?

Accepted Answer

$2$

Question 5

Which of the following best explains why $\mathrm{O_2}$ is paramagnetic?

Accepted Answer

It has two unpaired electrons in the $\pi^*_{2p}$ antibonding molecular orbitals.

Question 6

Which of the following is NOT a valid type of hybridization for atomic orbitals?

Accepted Answer

$sp^4$

Question 7

Which set of atomic orbitals can combine to form a $\pi$ bond?

Accepted Answer

Two parallel $p$ orbitals

Question 8

Which of the following best describes a bonding molecular orbital?

Accepted Answer

It is formed by the constructive interference (addition) of atomic orbitals, resulting in increased electron density between the nuclei.

Question 9

Which of the following molecules is predicted to be diamagnetic based on molecular orbital theory?

Accepted Answer

$\mathrm{N_2}$

Question 10

A molecule has a bond order of zero. What does this indicate about the molecule?

Accepted Answer

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

Question 11

Which of the following best explains the concept of electron delocalization in molecular orbital theory?

Accepted Answer

Electrons are spread over several atoms rather than being localized between two atoms.

Question 12

Which of the following is a correct statement about antibonding molecular orbitals?

Accepted Answer

They are higher in energy than the corresponding bonding molecular orbitals.

Question 13

Which of the following best describes the hybridization of the central atom in $\mathrm{BF_3}$?

Accepted Answer

$sp^2$

Question 14

Which of the following is the correct expanded octet hybridization for the central atom in $\mathrm{SF_6}$?

Accepted Answer

$sp^3d^2$

Question 15

Which of the following best explains why $\mathrm{O_2}$ is attracted to a magnet?

Accepted Answer

It has unpaired electrons, making it paramagnetic.

Question 16

Which of the following is the correct formula for calculating bond order using molecular orbital theory?

Accepted Answer

$\frac{	ext{number of bonding electrons} - 	ext{number of antibonding electrons}}{2}$

Question 17

Which of the following best describes the role of hybridization in the formation of methane ($\mathrm{CH_4}$)?

Accepted Answer

The carbon atom undergoes $sp^3$ hybridization to form four equivalent sigma bonds with hydrogen atoms.

Question 18

Which of the following best explains why the bond order of $\mathrm{O_2}^-$ (superoxide ion) is less than that of $\mathrm{O_2}$?

Accepted Answer

Adding an electron to $\mathrm{O_2}$ increases the number of electrons in antibonding orbitals, lowering the bond order.

Question 19

Which of the following is a real-world application of molecular orbital theory?

Accepted Answer

Explaining the paramagnetism of liquid oxygen in medical oxygen tanks.

Question 20

Which of the following best describes the difference between a bonding and an antibonding molecular orbital?

Accepted Answer

A bonding orbital has increased electron density between the nuclei, while an antibonding orbital has a node between the nuclei.

Chem - Chapter 6 study guide

Study Guide - Practice Questions