Question

Cation is smaller than netural
atom and anion is bigger then netural atom why?

Answer 1

Cations are formed by the loss of electrons hence protons are more than electrons in  cation.So electrons are strongly attracted by the nucleus and are pulled inward.Hence,the size decreases.

example:       Na - e⁻---> Na⁺

Anion is formed by the gain of electrons.Thus, the number of electrons are more than protons.The effective positive charge in the nucleus is less,so less inward pull is experienced.Hence the size expands.

example:      Cl + e⁻---> Cl⁻

hope this helps u.......................................

Answer 2

When a cation of an element is taken it loses an electron leaving the atom with less number of electrons than protons. So there will be more nuclear attraction by the nucleus to the electrons resulting in shrinking of the atom

When an anion of an element is taken it gains an electron leaving the atom with more electrons than protons. So there will be more electron electron repulsions and more shielding pushing the electrons further. So anion is bigger.

Hope it helps u