What does the term "oxidation" refer to in chemistry?

In chemistry, "oxidation" refers specifically to the process of losing electrons from a substance. This is a fundamental concept in redox (reduction-oxidation) reactions, where oxidation is always coupled with reduction, the gain of electrons by another substance. When an atom or molecule loses electrons, its oxidation state increases, reflecting this loss.

This transformation is crucial in various chemical reactions, such as combustion, respiration, and corrosion. It also highlights the role of electron transfer in energy transfer and the formation of chemical bonds. The understanding of oxidation, therefore, is vital when analyzing reactions and predicting products in a chemical process.

The other choices do not accurately describe oxidation. For instance, gaining neutrons is not related to redox reactions, and neither is gaining electrons, which is the definition of reduction. The change in temperature is indicative of energy changes during reactions but does not define oxidation.