Explain why cations are smaller and anions larger in radii than their parent atoms?

Explanation

The Ionic radius of cation is always smaller than the parent atom because the loss of one or more elecrons increases the effective nuclear charge. As a result the force of attraction of nucleus for the electrons increases and hence the ionic radii decrease. In contrast the ionic radius of an anion is always large than it parent atom because the addition of one or more elecrons decreases the effective nuclear charge . As a result , the force of attraction of the nucleus for the electrons decreases and hence the ionic radii increase.