What is the definition of oxidation in a chemical reaction?

Oxidation is defined as the removal of electrons from a species in a chemical reaction. This process leads to an increase in the oxidation state of the element that is undergoing oxidation. When electrons are removed from an atom or molecule, it becomes positively charged or less negatively charged. This fundamental concept is part of the broader framework of redox (reduction-oxidation) reactions, where one species is oxidized (loses electrons) and another is reduced (gains electrons).

The other choices pertain to different types of chemical processes. The addition of electrons refers to reduction, not oxidation. The formation of a new compound is a result of chemical reactions but does not specify whether oxidation or reduction occurs. The transfer of protons relates more closely to acid-base reactions rather than redox processes. Understanding these distinctions is crucial in the study of thermochemistry and the behavior of chemical species during reactions.