Elementary particle with a negative electrical elementary charge and a rest mass of 9.1094 · 10-31kg (corresponding to a self-energy of 511 keV). This is 1/1836 of the proton mass. Electrons surround the positively charged nucleus of an atom and determine the chemical behaviour of the atom. Occasionally, the negative electron is also called negatron and the electron used as a general term for negatron and positron.