A base in chemistry is a substance that can accept hydrogen ions (protons) or donate electron pairs, and typically reacts with acids to form salts. There are three main definitions of bases:
- Arrhenius bases : Substances that dissociate in water to produce hydroxide ions (OH⁻), which can neutralize hydrogen ions (H⁺) from acids. Examples include sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)₂)
- Brønsted–Lowry bases : Substances that act as proton (H⁺) acceptors. This definition includes bases that do not necessarily produce hydroxide ions, such as ammonia (NH₃)
- Lewis bases : Electron-pair donors that can share an electron pair with an electron acceptor (Lewis acid), broadening the concept beyond proton transfer
Common properties of bases include a bitter taste, slippery feel, the ability to turn red litmus paper blue, and having a pH greater than 7 in aqueous solutions
. Bases can be classified by the number of hydroxide ions they release per molecule: monoprotic (one OH⁻), diprotic (two OH⁻), or triprotic (three OH⁻)
. In summary, a base is a chemical substance that neutralizes acids by accepting protons or producing hydroxide ions, often resulting in a solution with pH above 7 and characteristic chemical behaviors
