Q: Calculate the bond order for the $$\mathrm{N_2$^+}$$ ion using the molecular orbital theory.

$$\displaystyle \text{Bond order} = \frac{9-4}{2} = 2.5$$

Question 1

Which of the following best describes the difference between a bonding molecular orbital and an antibonding molecular orbital formed from two atomic orbitals?

Accepted Answer

A bonding molecular orbital results from constructive interference, increasing electron density between nuclei, while an antibonding orbital results from destructive interference, creating a node.

Question 2

Given the molecular orbital diagram for $$\mathrm{O_2$}$$, which of the following statements is correct regarding its magnetic properties?

Accepted Answer

$$\mathrm{O_2$} is $$paramagnetic due to the presence of two unpaired electrons in the $$\pi^*$$ orbitals.

Question 3

Calculate the bond order for the $$\mathrm{N_2$^+}$$ ion using the molecular orbital theory.

Accepted Answer

$$\displaystyle 	ext{Bond order} = \frac{9-4}{2} = 2.5$$

Question 4

Which of the following molecules has a linear electron geometry according to VSEPR theory?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 5

What is the hybridization of the central atom in $$\mathrm{CH_3O^-}$$?

Accepted Answer

$$sp^3$$

Question 6

Which of the following Lewis structures for $$\mathrm{NO_2$^-}$$ best minimizes formal charges?

Accepted Answer

One oxygen has a double bond to nitrogen (0 charge), the other a single bond (-1 charge).

Question 7

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

Accepted Answer

It has unpaired electrons in the $$\pi^*$$ antibonding orbitals.

Question 8

Which of the following is the correct electron configuration for $$\mathrm{Fe$$^{3+}$$}$$?

Accepted Answer

$$[\mathrm{Ar}]\ 3d^5$

Question 9

Which of the following statements about resonance structures is correct?

Accepted Answer

The actual structure is a hybrid of all resonance forms, lowering the overall energy.

Question 10

Which of the following molecules or ions can expand its octet to minimize formal charge?

Accepted Answer

$$\mathrm{PO_4$^{3-}}$$

Question 11

Which of the following best describes the $$\pi-$$bonding interaction between two $$p$$ orbitals?

Accepted Answer

It is a side-by-side overlap, with electron density above and below the internuclear axis.

Question 12

Which of the following ions is isoelectronic with $$\mathrm{Ne}$$?

Accepted Answer

$$\mathrm{F^-}$$

Question 13

Which of the following best explains why $$\mathrm{NO} is a $$radical?

Accepted Answer

It has an odd number of electrons, resulting in one unpaired electron.

Question 14

Which of the following best describes the effect of adding electrons to antibonding orbitals?

Accepted Answer

It decreases bond order.

Question 15

Which of the following molecules has the highest bond order according to molecular orbital theory?

Accepted Answer

$$\mathrm{N_2$}$$

Question 16

Which of the following is the correct Lewis structure for $$\mathrm{PO_4$^{3-}}$$ that minimizes formal charges?

Accepted Answer

One oxygen is doubly bonded, three are singly bonded with negative charges.

Question 17

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

Accepted Answer

It has unpaired electrons in antibonding orbitals.

Question 18

Which of the following is the correct bond order for $$\mathrm{O_2$^-}$$?

Accepted Answer

$$\displaystyle \frac{9-6}{2} = 1.5$$

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