Question

radius of cation is smaller and that of anion is larger than the corresponding atom why

Answer 1

The size of an anion is larger than its parent atom because anions are formed due to the gain of electrons. When the electrons increase, there are still the same number of protons. The attractive force is thus reduced as there are the same number of protons attracting an increased number of electrons. This causes the electrons to not be bound as tightly to the nucleus resulting in an increase in size.

In other words, anions have one or more extra electrons that contribute to the size of the atom. These extra electrons increase its size and make it larger than the neutral atom.

Answer 2

In case of cation electrons are donated so its shell get removed while in case of anion electrons are gained and its shell get increased so the size of anion is larger than the cation