What is a Free Radical?
A free radical is an atom, molecule, or ion that has at least one unpaired valence electron. This unpaired electron makes free radicals highly unstable and extremely reactive, as they constantly seek to gain or lose an electron to achieve a more stable electron configuration, typically by reacting with other molecules.
Characteristics and Formation of Free Radicals
Due to their unpaired electron, free radicals can participate in chain reactions, often extracting an electron from another molecule, which then becomes a new free radical. They are commonly formed during normal metabolic processes, through exposure to environmental factors like pollution, radiation, or tobacco smoke, and as intermediates in various chemical reactions.
Free Radicals in Biological Systems: An Example
A common example is the superoxide radical (O₂•⁻), formed in biological systems as a byproduct of oxygen metabolism. This radical can damage cells, DNA, and proteins, contributing to aging and diseases like cancer and heart disease. Antioxidants, found in fruits and vegetables, help neutralize these free radicals by donating an electron without becoming unstable themselves.
Importance and Impact Across Disciplines
While often associated with cellular damage, free radicals also play beneficial roles, such as in immune responses where they are used to destroy pathogens. In industrial chemistry, they are crucial for polymerization reactions to create plastics. Understanding free radicals is vital across fields from medicine to materials science due to their pervasive and powerful reactivity.