electron

The electron is an elementary subatomic particle that carries a negative electrical charge. The concept of a least possible amount of electrical charge was theorized on several occasions, beginning in 1838 by British natural philosopher Richard Laming; the name electron was introduced in 1894 by Irish physicist George Johnstone Stoney.[8] The electron was first identified in 1897 by J. J. Thomson and his team of British physicists.[6][9] These charged particles, together with atomic nuclei made of protons and neutrons, make up atoms. Interaction among the electrons of two or more atoms is the main cause of chemical bonding. Electrons play an essential role in many physical phenomena such as electricity, magnetism, and thermal conductivity.[10]

Electrons have no known substructure and are believed to be point particles.[2] They are identical particles that belong to the first generation of the lepton particle family. Each electron carries a negative elementary charge and participates in electromagnetic and weak interactions. The components of its spin, or intrinsic angular momentum, can have values of ±1⁄2 ħ, where ħ is the reduced Planck constant; for this reason, electrons are classified as spin-1⁄2 particles. A consequence of this is the Pauli exclusion principle, stating that no two electrons can occupy the same quantum state at any one time. The mass of an electron is approximately 1⁄1836 of a proton.[11]

The properties of the electron are determined by observing its interaction with other particles. The attractive Coulomb force between an electron and a proton is what causes electrons to be bound into atoms. When an electron is in motion, it both generates a magnetic field and is deflected by external magnetic fields. Electrons have quantum mechanical properties of both a particle and a wave, so they can collide with other particles and be diffracted like light. While an electron is undergoing acceleration, it can absorb or radiate energy in the form of photons. In the collision of an electron and a positron, the electron's antiparticle, both are annihilated. An electron–positron pair can be produced from gamma ray photons with a combined energy at least equal to the energy at rest of the particles.[