electron

electron [ē lek′trän΄, ilek′trän; ] also [, ē lek′trən, i lek′trən]

n.

[coined (1891) by G. J. Stoney (1826-1911), Ir physicist < ELECTR(IC) + -ON]

Particle Physics the lightest elementary particle with an electric charge: it is a lepton with a negative charge of c. 1.602 × 10^-19 coulomb and a rest mass of c. 9.109 × 10^-31 kg ( c. 0.511 MeV/c²), which is c. ¹/ ₁₈₃₆ of the mass of a proton: ordinarily an atom has the same number of negative electrons around the nucleus as the number of positive protons in the nucleus: see also POSITRON, NEGATRON