Free radicals are molecules in which their outer shell has one or more unpaired electrons and can be formed in certain ways:
Heterolytic cleavage of a molecule ensures the formation of carbocations and carbanions where carbanions have two electrons while carbocations have zero electrons.
However free radicals are formed by the homolytic cleavage of a molecule where each fragment has an equal number of electrons.
Free radical formation usually takes place in the presence of light like Ultraviolet rays.
