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 1{{s}^{1}},\sigma 1{{s}^{1}},\overset{*}{\mathop{\sigma }}\,1{{s}^{0}} $ Bond order $ =\frac{1}{2} $ $ H_{2}^{-}:\sigma 1{{s}^{2}},\overset{*}{\mathop{\sigma }}\,1{{s}^{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}^{-} $ .