Subatomic particle - Electron, Muon, Tau | Britannica
Probably the most-familiar subatomic particle is the electron, the component of atoms that makes interatomic bonding and chemical reactions—and hence life—possible. The electron was also the first particle to be discovered. Its negative charge of 1.6 × 10−19 coulomb seems to be the basic unit of electric charge, although theorists have a poor understanding of what determines this particular size. The electron, with a mass of 0.511 megaelectron volts (MeV; 106 eV), is the lightest of the charged leptons. The next-heavier charged lepton is the muon. It has a mass of 106 MeV, which is some 200 times greater than the electron’s mass but is significantly less than the proton’s mass of 938 MeV. Unlike the electron, which appears to be completely stable, the muon decays after an average lifetime of 2.2 millionths of a second into an electron, a neutrino, and an antineutrino. This process, like the beta decay of a neutron into a proton, an electron, and an antineutrino, occurs via the weak for