In a redox reaction, what does oxidation refer to?

In a redox (reduction-oxidation) reaction, oxidation refers specifically to the loss of electrons. When an atom or molecule undergoes oxidation, it becomes more positive in charge because the removal of negatively charged electrons results in a higher net positive charge. This process is crucial in redox reactions as it is always coupled with a reduction process, where another atom or molecule gains the electrons that were lost.

The concept of "oxidation" originally stems from reactions involving oxygen but has been expanded to include electron transfer in general. Thus, in the context of redox reactions, understanding oxidation as the loss of electrons is fundamental, as it helps in balancing the reactions and understanding the flow of electrons, which is key to various chemical processes including those in electrochemistry and metabolic pathways.