Question

explain why cations are smaller and anions are larger in radii then their parents atoms

Answer 1

Atoms are having a fixed no of electrons in each shell.

Ions are electrically charged particles formed due to gaining, losing or sharing of electrons.

Cations are formed due to losing of electrons fromtheir outermost shell, therefore reducing its radius.

Similarly......

Anions are formed due to gaining of electrons in their outermost shell, therefore increasing its radius.

Hope it helps....