Question

Comment on the nature of two S−O bonds formed in SO₂ molecule. Are the two S−O bonds in this molecule equal?

Answer 1

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

During the formation of SO₂, one electron from 3p orbital goes to the 3d orbital and S undergoes sp²hybridization. Two of these orbitals form sigma bonds with two oxygen atoms and the third contains a lone pair. p-orbital and d-orbital contain an unpaired electron each. One of these electrons forms pπ- pπ bond with one oxygen atom and the other forms pπ- dπ 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.

Both S−O bonds are equal in length (143 pm) and have a multiple bond character.

Answer 2

 SO₂ exists as an angular molecule with OSO bond angle of 119.5°. It a resonance hybrid of two canonical-forms:

Due to resonance the to π bonds are equal.