Cation is smaller than neutral atom and anion is larger than neutral atom. Why?

Suppose there are ‘N’ number of electrons present in a neutral atom. The N electrons are held together by the nucleus.

Cation is the ion obtained by the removal of electron from a neutral atom. When an electron is removed, then there exists N-1 electrons. As a result there will be an increase in effective nuclear charge over the remaining electrons, and hence the size of cation is smaller than the size of neutral atom.

Anion is the ion obtained by adding an electron to the neutral atom. When the electron is added, then there will be N+1 electrons. Here, the effective nuclear charge is decreased over the electrons. Therefore, the size of anion is larger than that of the neutral atom.