What defines oxidation in chemical reactions?

Oxidation in chemical reactions is defined as the loss of one or more electrons. This definition is fundamental in the study of redox reactions, where oxidation and reduction occur simultaneously. When a substance loses electrons, it increases its oxidation state, which is a key characteristic of oxidation.

In contrast, the other options do not accurately reflect the concept of oxidation. Gaining electrons is associated with reduction, not oxidation. The movement of electrons from anode to cathode describes the flow of current in an electrochemical cell rather than specifically defining oxidation. Additionally, the reaction at the cathode is related to reduction, as that is where electrons are accepted, reinforcing the idea that oxidation involves the loss of electrons. Understanding these definitions is crucial in the field of electrochemistry and for interpreting various chemical processes.