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

1. ${\mathrm{H}}_2^{2-}$
2. ${\mathrm{He}}_2^{2+}$
3. ${\mathrm{He}}_2^{+}$
4. ${\mathrm{H}}_2^{-}$

Solution

The electronic configuration of ${\mathrm{H}}_2^{2\ominus }$ is $\Rightarrow \left(\mathrm{\sigma }1{\mathrm{s}}^2\right),\mathrm{ }{\left({\mathrm{\sigma }}^{\mathrm{*}}1\mathrm{s}\right)}^2$



Bond order of ${\mathrm{H}}_2^{2⊝}=\frac{{\mathrm{N}}_{\mathrm{b}}-{\mathrm{N}}_{\mathrm{a}}}{2}=\frac{2-2}{2}=0$

Hence, ${\mathrm{H}}_2^{2\ominus }$ does not exist, due to zero bond order.

Asked in: JEE Main 2018 (08 Apr)

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