Define atomic size. How does it vary in a period and in a group?

1.      Define atomic size. How does it vary in a period and in a group?

Ans.

i.                    Atomic size is determined by the atomic radius.

ii.                  For an isolated atom, its atomic radius is the distance between the centre of the atom (i.e. centre of its nucleus) and its outermost shell.

iii.                Generally, in the period, the atomic radius decreases from left to right.

iv.                 In a group, the atomic radius increases from top to bottom.