The electronic configuration of S is 1s² 2s² 2p⁶ 3s² 3p⁴.

One electron from 3p orbital goes to the 3d orbital and S undergoes sp² hybridization, during the formation of SO₂ molecule. Two of these orbitals form sigma bonds with two oxygen atoms and the third contains a lone pair of electrons. The p-orbital and d-orbital contain an unpaired electron each. An electron in the p-orbital forms p π- p π bond with one oxygen atom and the other electron forms p π- d π bond with the other oxygen. This is the reason SO₂ has a bent structure. Also, it is a resonance hybrid of structures I and II, with equal bond lengths of 143pm.