Question

The size of atomic radius increases down the group because

Answer 1

On going down the group, the no of shells increase i.e. K, L, M, N... hence the distance of last orbit from nucleus increases, which leads to increase in atomic radius of the atom

Answer 2

The number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases as the group and energy levels increase.