What does oxidation refer to in a chemical reaction?

In chemistry, oxidation refers to the loss of electrons by a substance during a chemical reaction. This concept is fundamental to understanding redox reactions, where one species is oxidized (loses electrons) while another is reduced (gains electrons). When a substance undergoes oxidation, its oxidation state increases because the removal of negatively charged electrons results in a more positive charge.

This process is essential in various chemical and biological contexts, such as in cellular respiration and combustion reactions, where substances lose electrons and release energy in the process. The relationship between oxidation and reduction can be summed up with the mnemonic "OIL RIG" (Oxidation Is Loss, Reduction Is Gain), highlighting that oxidation is indeed associated with the loss of electrons.