The term "amphoteric" refers to a substance or compound that can act as both an acid and a base. It is derived from the Greek words "ampho" meaning "both" and "teros" meaning "ends." Amphoteric substances have the ability to donate or accept protons (H+) depending on the nature of the reactants they encounter.
When an amphoteric substance reacts with an acid, it behaves as a base by accepting a proton. Conversely, when it interacts with a base, it acts as an acid by donating a proton. This dual nature allows amphoteric compounds to exhibit different chemical properties depending on the conditions and the substances they come into contact with.
A well-known example of an amphoteric substance is water (H2O). Water can act as both an acid and a base. In an acidic solution, water can act as a base by accepting a proton from the acid. In a basic solution, water can act as an acid by donating a proton. Other examples of amphoteric compounds include amino acids, aluminum hydroxide, and zinc oxide.