What is radical and what is an ion?

Ions are atoms or molecules which have gained or lost one or more valence electrons, giving the ion a net positive or negative charge.

• Cations are positively charged ions. They are formed when a metal loses its electrons. They lose one or more than one electron and do not lose any protons. Therefore they possess a net positive charge. Some examples of cations are Calcium (Ca2+), Potassium (K+), hydrogen (H+).

• Anions are negatively charged ions. They are formed when a nonmetal gains electrons. They gain one or more than one electron. Therefore they possess a net negative charge. Some examples of anions are Chloride ions (Cl-), iodide(I-), Bromide ions (Br-).

A Free radical is an atom or a group of atoms containing one or more unpaired electron(s). They are highly reactive due to the presence of an unpaired electron. Free radicals are very unstable and try to gain stability by accepting the needed electron. For example,  H, Cl HO, CH₃.