Reduction refers to what in terms of electron transfer?

Reduction is defined in the context of electron transfer as the addition of electrons to a species. This process involves a species gaining electrons, which leads to a decrease in its oxidation state. In a redox reaction, when one species is reduced, another species must be oxidized, meaning it loses electrons.

Understanding reduction is crucial for grasping redox chemistry, as it helps explain how energy is transferred in chemical reactions. For example, in a reduction-oxidation (redox) reaction, an oxidizing agent is one that gains electrons (is reduced), while a reducing agent is one that loses electrons (is oxidized). Therefore, associating reduction with the addition of electrons clarifies the role of various species in chemical reactions and highlights the critical nature of electron flow in thermodynamic processes.