Some reactions of alkanes involve a free radical mechanism - Leaving Cert Chemistry - Question (i) - 2001

A free radical is a species that has one or more unpaired electrons, making it highly reactive. These radicals are often formed through a process called homolysis, which is the equal splitting of a bond. When a bond between two atoms is broken, each atom retains one of the shared electrons, resulting in two free radicals.

Example of a Free Radical

An example of a free radical is the chlorine atom (Cl•). In a reaction where chlorine molecules (Cl2) undergo homolysis due to heat or light, each chlorine atom can form a free radical, represented as Cl•.