Question

The correct electronic configuration for $H_2^{-}$ is:

• A. $\sigma \left({1s}^1\right){\sigma }^{\ast }({1s}^1$)
• B. $\sigma {1s}^3$
• C. $\sigma \left({1s}^2\right){\sigma }^{\ast }\left(1s^1\right)$
• D. $\sigma {1s}^2$

Answer 1

The correct option is C $\sigma \left({1s}^2\right){\sigma }^{\ast }\left(1s^1\right)$

As per the molecular orbital diagram:
Electronic configuration of $H_2$ is: $\sigma (1s{)}^2$
When one electron is added to hydrogen molecule, the
electronic configuration of $H_2^{-}$ is: $\sigma \left(1s{)}^2{\sigma }^{\ast }\right(1s^1)$