Question

According to molecular orbital theory, which of the following will not be a viable molecule?

• A. $H_2^{-}$
• B. $H_2^{2-}$
• C. $H{e}_2^{2+}$
• D. $H{e}_2^{+}$

Answer 1

The correct option is B $H_2^{2-}$

Electronic configuration of $H_2{}^{2-}=\left(\sigma 1s^2\right)\left({\sigma }^{\ast }1s^2\right)$

Bond order of $H_2^{2⊝}=\frac{N_b-N_a}{2}=\frac{2-2}{2}=0$.

If a bond order of zero is obtained, that means that the molecule is too unstable and so it will not exist.

Hence, $H_2^{2⊝}$ does not exit, due to zero bond order.

Option B is correct.