Free radical

A free radical is a molecule with an unpaired electron. The molecule is reactive and seeks another electron to pair. Free radicals are involved in the mechanisms of damage associated with disease development. Examples are hydrogen peroxide, hypochlorite, nitric oxide and nitrogen dioxide. 
A radical is an atom or group of an (?) which possesses electric charge. There are two types of radicals: Cation and anion. Cation are positively charged while anion are negatively charged. Examples of cation are Calcium (Ca2+), Potassium (K+), Hydrogen (H+). Examples of anion are Iodide (I-), Chlorine (Cl-) and Hydroxide (OH-). 
The need for antioxidants in peoples’ daily life is becoming more critical with increased exposure to free radicals. Pollution, cigarette smoke, drugs, illness and stress can increase our exposure.