Question

atomic radius of Ga is less than that of Al Why?

Answer 1

We aspect that when we move down the group the size of the atom must increase due to addition of a new subshell but this is not happen in this case ...this is due to the presence of additional d-orbital electrons in gallium and they produce a poor shielding effect due to which outer electrons feel much attraction towards nucleus and hence size becomes smaller ...Hope this will help u dear

Answer 2

Size of GA is less than Al due to poor screening effect.. While going from Al to GA..... Electrons already occupied 3d sub shell in GA.. So GA is slightly lesser in size than Al