Oxidation and reduction are complementary chemical processes that involve a loss of electrons (oxidation) by one reactant and a corresponding gain (reduction) by another. Both processes must occur simultaneously and in equivalent amounts. The most familiar oxidative processes utilize oxygen from the atmosphere; these include the rusting of iron, combustion, and respiration in each case oxygen is reduced. Reductive processes include the recovery of metals from their ores, the photosynthetic production of carbohydrates, and the hydrogenation of fats. Oxidizing Agents The substance that acquires electrons during an oxidation-reduction reaction is an oxidizing agent. In the course of the reaction, the oxidizing agent react and become weak reducing agent. Of the chemical elements, the most electronegative elements have the greatest tendency to participate in reactions as oxidizing agents, because they form negative ions very readily. Fluorine, with with the most highly electronegative a