The total number of electrons in all bonding molecular orbitals of $\mathrm{O}_{2}^{2-}$ is \_\_\_\_. (Round off to the Nearest Integer).

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Chemical Bonding and Molecular Structure

The total number of electrons in all bonding molecular orbitals of

O_{2}^{2 -}

is ____.
(Round off to the Nearest Integer).

Answer: 10

The peroxide ion

O_{2}^{2 -}

holds

8 + 8 + 2 = 18

electrons, which fill the molecular orbitals as

σ_{1 s}^{2} σ_{1 s}^{* 2} σ_{2 s}^{2} σ_{2 s}^{* 2} σ_{2 p_{z}}^{2} π_{2 p_{x}}^{2} π_{2 p_{y}}^{2} π_{2 p_{x}}^{* 2} π_{2 p_{y}}^{* 2}

The bonding orbitals here are

σ_{1 s}

σ_{2 s}

σ_{2 p_{z}}

π_{2 p_{x}}

and

π_{2 p_{y}}

, five orbitals carrying two electrons each. The total number of electrons in bonding molecular orbitals is

10

JEE Main · 2021 · 27 Jul 2021 · Shift 2 · Integer answer