In physics, the electron volt (symbol eV; also written electronvolt according to the NIST, IUPAC,[1] and BIPM[2]) is a unit of energy. By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an electrostatic potential difference of one volt. Thus it is 1 volt (1 joule divided by 1 coulomb) multiplied by the electron charge, 1.60217653(14)×10−19 coulomb. One electron volt is equal to 1.60217653(14)×10−19 joules.[3]
The electron volt is not an SI unit and its value must be obtained experimentally.[4] It is the most common unit of energy within physics, widely used in solid state, atomic, nuclear, and particle physics. It is commonly used with SI prefixes milli, kilo, mega, giga, tera, or peta (meV, keV, MeV, GeV, TeV and PeV respectively).
In chemistry, it is often useful to have the molar equivalent, that is the kinetic energy that would be gained by a mole of electrons passing through a potential difference of one volt. This is equal to 96.48538(2) kJ/mol. Atomic properties like the ionization energy are often quoted in electron volts.
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