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 $H_{2}^{-}$

Hint:

Antibonding electrons decrease the stability of a molecule or ion.

Answer 1

The Correct Option is D

Step 1: Bond Order
The bond order for both $H_{2}^{+}$ and $H_{2}^{-}$ is calculated to be $1/2$.
Step 2: Electron Configuration
$H_{2}^{+}$ has the configuration $\sigma 1s^{1}$. $H_{2}^{-}$ has the configuration $\sigma 1s^{2}, \sigma^{*} 1s^{1}$.
Step 3: Stability Analysis
Although the bond orders are the same, $H_{2}^{-}$ is less stable than $H_{2}^{+}$ because it contains an electron in the antibonding molecular orbital ($\sigma^{*} 1s$), which increases repulsion and decreases stability.
Final Answer: (d)