Chapter 9, Problem 9.59P

Interpretation Introduction

Interpretation:

The energetically least stable compound has to be identified.

Concept Introduction:

Bond order $\text{=}\frac{\left({\text{N}}_{\text{b}}\right)\text{-}\left({\text{N}}_{\text{a}}\right)}{\text{2}}$

Where, ${\text{N}}_{\text{b}}$ is number of electrons in bonding orbital.

${\text{N}}_{\text{a}}$ is number of electrons in antibonding orbital.

  $\text{Bond}\text{order}\text{α}\text{Bond}\text{energy}\text{α}\frac{\text{1}}{\text{Bond}\text{length}}$

As the bond order decreases, the bond decreases too.  Because of that triple bonds between atoms are shorter than double bonds because it requires more energy to completely break all three bonds than to break two.  But triple bonds are also stronger than double bonds.  The same is with the double bonds and single bonds.

As bond order decreases, the bond length increases.  A large amount of energy has to use large energy to triple bond than double bond.  That is why triple bonds are shorter.