The electronvolt (symbol eV) is a unit of energy. It is the amount of energy equivalent to that gained by a single unbound electron when it's accelerated through an electrostatic potential difference of one volt, in vacuo. In other words, it's equal to one volt (1 volt = 1 joule per coulomb) multiplied by the (unsigned) charge of a single electron. The one-word spelling is the modern recommendation, although the use of the earlier electron volt still exists. One electronvolt is a very small amou… (More on Electronvolt)