SO2 as a Lewis Acid

[Hooman]

How is SO2 a lewis acid when there is a lone pair of electrons on the S? NH3 has a lone pair on the central atom, making it a lewis base, but the same logic does not apply to SO2.

[Srinidhi Sampath 1G]

Hello! The determination of a molecule as a Lewis acid or base doesn't just depend on the number of lone pairs it has, but rather its ability to donate or accept electrons. Even though sulfur in SO₂ has a lone pair, it can act as a Lewis acid due to its ability to accept electron pairs through the sulfur atom. This occurs because the sulfur in SO₂ has an incomplete octet in its bonding framework. NH₃, on the other hand, has a lone pair on nitrogen. This lone pair can easily be donated to form a bond with an electron pair acceptor, making it a Lewis base. Hope this helps!