Chapter 9.6, Problem 3CP

Interpretation Introduction

Interpretation: The bond order of ${\text{He}}_{\text{2}}{}^{+}$

is to be determined.

Concept introduction:

The combination of two atomic orbitals results in the formation of a bonding, and an antibonding molecular orbital. Orbitals that lie on an internuclear axis combine to form sigma, $\sigma$, molecular orbital, and orbitals parallel to each other combine to form $\pi$

molecular orbitals.

The molecular orbital formed by the combination of $\text{1s}$ orbital forms bonding molecular orbital, designated as ${\sigma }_{1s}$, and antibonding molecular orbital, designated as ${\sigma }^{\ast }{}_{1s}$. The $\text{2s}$ orbital forms corresponding molecular orbitals.

Bond order is determined by subtracting the number of antibonding electrons from the number of bonding electrons and dividing the number obtained by two.

Bond order $=\left({\text{N}}_{\text{b}}-{\text{N}}_{\text{a}}\right)/\text{2}$, where ${\text{N}}_{\text{b}}$ is the number of bonding electrons and ${\text{N}}_{\text{a}}$ is the number of antibonding electrons.