An atom or group of atoms with at least one unpaired electron; SYN. radical.
In chemistry, an atom or molecule that has an unpaired electron and is therefore highly reactive. Most free radicals are very short-lived. They are by-products of normal cell chemistry and rapidly oxidize other molecules they encounter. They are thought to do considerable damage. They are neutralized by protective enzymes.
Free radicals are often produced by high temperatures and are found in flames and explosions.
A very simple free radical is the methyl radical CH3 produced by the splitting of the covalent carbon-to-carbon bond in ethane. CH3CH3 Ű 2CH3.