Question

In $O^{-}_{2}$, $O_{2}$ and $O^{2-}_{2}$ molecular species. Find the total number of antibonding electrons

Answer 1

Molecular orbital electronic configuration of these species are :
$O^{-}_{2} (17 e^{-}) : \sigma 1s^{2}, \sigma^{*} 1s^{2}, \sigma 2s^{2}, \sigma^{*}2s^{2}, \sigma2p^{2}_{z}$,
$\pi 2p^{2}_{x}= \pi2p^{2}_{y}, \pi^{*} 2p^{2}_{x} = \pi^{*} 2 p^{1}_{y}$
$O_{2} (16e^{-}) : \sigma 1s^{2}, \sigma^{*}\,1s^{2}, \sigma 2s^{2}, \sigma ^{*} 2s^{2}, \sigma 2p^{2}_{z}$,
$\pi 2P^{2}_{x}= \pi 2p^{2}_{y}, \sigma^{*}\,2 p^{1}_{x}=\pi^{*}\,2p^{1}_{y}$
$O^{2-}_{2}(18e^{-}) : \sigma 1s^{2}, \sigma^{*}1s^{2}, \sigma2s^{2}, \sigma^{*}2s^{2}, \sigma2p^{2}_{z}$,
$\pi 2p^{2}_{x} : \pi 2p^{2}_{y}, \pi^{*}2p^{2}_{x}=\pi^{*}2p^{2}_{y}$
Hence number of antibonding electrons are $7, 6$ and $8$ respectively