Q: What is the bond order formula according to molecular orbital theory?

$\text{Bond Order} = \dfrac{\text{number of bonding electrons} - \text{number of antibonding electrons}}{2}$

Question 1

Which of the following statements best describes the main limitation of Lewis structures in predicting molecular geometry?

Accepted Answer

Lewis structures cannot predict the three-dimensional shape of molecules and do not account for the role of orbitals.

Question 2

According to the VSEPR model, what is the electron-pair geometry around a central atom with a steric number of 4 and no lone pairs?

Accepted Answer

Tetrahedral

Question 3

Which molecule would exhibit a bent molecular structure due to the presence of lone pairs, given a steric number of 3?

Accepted Answer

Cl$_2$C (dichlorocarbene)

Question 4

Why do lone pairs compress the bond angles between bonding pairs in a molecule?

Accepted Answer

Lone pairs are closer to the nucleus and require more space than bonding pairs.

Question 5

What is the expected bond angle in a molecule with a tetrahedral electron-pair arrangement but one lone pair on the central atom?

Accepted Answer

Less than $109.5^\circ$

Question 6

Which hybridization is required for a central atom surrounded by three effective pairs of electrons?

Accepted Answer

sp$^2$

Question 7

A carbon atom in ethene (C$_2$H$_4$) forms a double bond with another carbon atom. What types of bonds and hybridization are present in this double bond?

Accepted Answer

One sigma bond (sp$^2$) and one pi bond (unhybridized p)

Question 8

Which molecular geometry is associated with a dsp$^3$ hybridization?

Accepted Answer

Trigonal bipyramidal

Question 9

Using the molecular orbital (MO) theory, what is the bond order of the H$_2^+$ ion?

Accepted Answer

$0.5$

Question 10

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

Accepted Answer

O$_2$

Question 11

A molecule has a center of positive charge and a center of negative charge. What property does this molecule possess?

Accepted Answer

It has a dipole moment.

Question 12

Which of the following best explains why CO$_2$ is a nonpolar molecule despite having polar bonds?

Accepted Answer

The molecule has no dipole moment because the bond polarities cancel each other out.

Question 13

What is the bond order formula according to molecular orbital theory?

Accepted Answer

$	ext{Bond Order} = \dfrac{	ext{number of bonding electrons} - 	ext{number of antibonding electrons}}{2}$

Question 14

Which hybridization is associated with a central atom in SF$_6$ (sulfur hexafluoride)?

Accepted Answer

d$^2$sp$^3$

Question 15

In the molecular orbital diagram for O$_2$, why is the molecule paramagnetic?

Accepted Answer

There are unpaired electrons in the $	ext{2p}^*$ antibonding orbitals.

Question 16

Which of the following molecules is expected to have a trigonal bipyramidal electron-pair arrangement?

Accepted Answer

PCl$_5$

Question 17

A molecule of XeF$_4$ has six electron domains around the central atom. What is its electron-pair geometry and hybridization?

Accepted Answer

Octahedral, d$^2$sp$^3$

Question 18

Which statement about molecular orbitals is correct?

Accepted Answer

Antibonding molecular orbitals are higher in energy than the atomic orbitals from which they are formed.

Question 19

Which of the following best describes the difference between paramagnetism and diamagnetism?

Accepted Answer

Paramagnetism is associated with unpaired electrons and attraction to a magnetic field; diamagnetism is associated with paired electrons and repulsion from a magnetic field.

Molecular Structure and Orbitals: VSEPR Theory and Hybridization

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