Why do group 12 elements have different properties that group 13?

The group 12 elements have an electronic configuration of nd10(n+1)s2. The group 13 elements have the configuration of nd10(n+1)s2(n+1)p1. The group 12 elemnts Zn, Cd and Mercury have only 2 valence electrons, (s electrons). Group 13 elemnts B, Al, Ga, In Tl have 3 valence electrons, s2 p1.

The chemistry of the groups is therefor different.