What is a radical in chemistry?

In chemistry, a radical is defined as a particle that has an unpaired electron. This characteristic makes radicals highly reactive, as they tend to seek out other electrons to pair with, leading to a variety of chemical reactions. The unpaired electron is often responsible for the radical's ability to participate in oxidation-reduction reactions and can initiate chain reactions, such as those seen in combustion processes or in the formation of complex organic molecules.

Radicals can exist in many forms, such as alkyl radicals, alkoxy radicals, and others. Their reactivity is a key feature that distinguishes them from other species such as stable molecules, which generally have all their electrons paired. Understanding radicals is important in organic chemistry and various fields, including biochemistry, where they play roles in processes like cellular respiration and oxidative stress.