How are free radicals formed when a covalent bond breaks evenly?

When a covalent bond—which typically consists of a shared pair of electrons—breaks evenly, the process is known as homolysis.1

During this cleavage, the shared electron pair is split equally between the two atoms or groups that were previously linked by the bond. As a result, each of the two resulting entities retains one of the electrons from the original bond, creating two separate species that each contain a single, unpaired electron. These resulting chemical entities are called free radicals.12

Because of these unpaired electrons, free radicals are generally highly reactive and often exist only as transient intermediates in chemical reactions. This homolytic mechanism is distinct from heterolysis, where the electron pair is not split evenly but instead remains with only one of the two fragments.231