Question

The correct statement with regard to $H_2^{+}$ and $H_2^{-}$ is

• A. both $H_2^{+}$ and $H_2^{-}$ are equally stable
• B. both $H_2^{+}$ and $H_2^{-}$ do not exist
• C. $H_2^{-}$ is more stable than $H_2^{+}$
• D. $H_2^{+}$ is more stable than $H_2^{-}$

Answer 1

Answer: (D)

$H_2^{+}:\sigma 1s^1,\sigma 1s^1,\stackrel{\ast }{\sigma }1s^0$ Bond order $=\frac{1}{2}$ $H_2^{-}:\sigma 1s^2,\stackrel{\ast }{\sigma }1s^1$ Bond order $=\frac{2-1}{2}=\frac{1}{2}$ The bond order of $H_2^{-}$ and $H_2^{-}$ are same but $H_2^{+}$ is more stable than $H_2^{-}$ . It is due to the presence of one electron in the anti bonding molecular orbital in $H_2^{-}$ .