Electron

The electron is a stable subatomic particle carrying one negative unit of Electric charge. It is the lightest charged Lepton, and every neutral Atom carries as many electrons as protons. Chemistry — bonding, conduction, all of it — is electrons doing the work.

Properties

property	value	note
electric charge	−1 e = −1.602 176 634 × 10⁻¹⁹ C	exact by SI definition since 2019
rest mass	9.109 383 7139 × 10⁻³¹ kg	≈ 1/1836 of the proton
spin	½ ħ	a fermion — obeys the Pauli exclusion principle
antiparticle	Positron	same mass, opposite charge
lifetime	stable	no decay ever observed

Why it matters

• Chemistry is the behavior of the outermost electrons of atoms.
• Electricity in a wire is electrons drifting through a metal lattice.
• Electronics work by steering electrons through semiconductors.
• The photo above is electrons made visible: a beam bent into a circle by a magnetic field in a Teltron tube.

Discovery

J. J. Thomson identified the electron in 1897 through cathode-ray experiments at the Cavendish Laboratory, showing the rays were particles far lighter than any atom. He called them "corpuscles"; the name electron (G. Johnstone Stoney's coinage) stuck instead.