During change of O₂ to O₂⁻ ion, the electron adds on which one of the following orbitals?

Options

(a) π* orbital
(b) π orbital
(c) σ* orbital
(d) σ orbital

Correct Answer:

π* orbital

Explanation:

O₂ = KK (σ2s)² (σ*2s)² (σ2pₖ)²
(π2pᵢ)² (π2pⱼ)² (π*2pᵢ)¹ (π*2pⱼ)¹
O₂⁻ = KK (σ2s)² (σ*2s)² (σ2pₖ)²
(π2pᵢ)² (π2pⱼ)² (π*2pᵢ)² (π*2pⱼ)¹