Question

Using MO theory predict which of the following species has the shortest bond length?

• A. $O_{2}^{+}$
• B. $O_{2}^{-}$
• C. $O_{2}^{2 -}$
• D. $O_{2}^{2 +}$

Answer 1

Answer: (D)

Bond length $\propto \frac{1}{ \text {bond order }}$
Bond length $=\frac{ \text { no. of bonding } \bar{e}-\text { no. of antibonding } \bar{e}}{2}$
Bond orders of $O_{2}^{+}, O_{2}^{-}, O_{2}^{2-}$ and $O_{2}^{2+}$ are respectively $2.5$, $1.5,1$ and $3$
Hence $O_{2}^{2+}$ is shortest in bond length as have max. bond order.