Question

what happens when increasing the atomic number in group 1A [Concerning the atomic size] ​

Answer 1

Answer: Size increases down the group.

Explanation:

Down the group (any group in fact), the number of principal quantum shells increases, this means that the valence electron is further away from the nucleus. Since the atomic radius is defined as the distance between the nucleus and the valence electron, the further the electron the larger the radius. Hence, the atomic size increases down the group.