The atomic size of an element increases down the group while along a period, it tends to decrease. Explain.

The atomic size of elements of group 2 compared to group 1 element are

(a) Define the following terms: (i) Valency, (ii) Atomic size (b) How do the valency and the atomic size of the element vary while going from left to right along a period in the modern periodic table?

On moving along the period , the atomic radii decreases