Atomic radius of chlorine atom is 0.99 Å but ionic radius of chloride `(Cl^(-))` is 1.81 Å-explain.

Explanation

In a anion, total number of electrons being greater then that of the number of protons, attraction of the nucleus for the outermost electrons decreases. Furthermore, due to mutual repulsion among electrons, outermost orbit gets appreciably expanded. As a result anionic radius becomes more than the radius of the parent atom. on account of this, radius of `Cl^(-)(1.81"Å")` (18 electrons and 17 protons) is greater than the radius of chlroine (0.99Å) atom (17 electrons and 17 protons).