Electron

A stable elementary particle belonging to the first generation of the “lepton” family of particles. It has a -1 electrical charge, while its anti-particle, the anti-electron or positron, has a +1 electrical charge. Atoms are made of electrons orbiting positively charged nuclei. An electron has a mass of $\sim 0.5 MeV/c^2$, or about $1/1836$ times the mass of a proton.