Electron transfer
Electron transfer is one of the simplest forms of a chemical reaction. It consists of one outer-sphere electron transfer between substances of the same atomic structure likewise to Marcus’s studies between bivalent and trivalent iron ions. Electron transfer may be one of the most basic forms of chemical reaction but without it life cannot exist. Electron transfer is used in all respiratory functions as well as photosynthesis. In the process of oxidizing food molecules, two hydrogen ions, two electrons, and an oxygen molecule react to make an exothermic reaction as well as H2O (water). Due to fact that electron transfer is such a broad, common, and essential reaction within nature, Marcus's theory has become vital within the field of chemistry.