Wikipedia:Today's featured article/November 21, 2009



An electron is a subatomic particle that carries a negative electric charge. It has no known substructure and is believed to be a point particle. An electron has a mass that is approximately 1/1836 that of the proton. The intrinsic angular momentum (spin) of the electron is a half integer value of $1/2$, which means that it is a fermion. Electrons, which belong to the first generation of the lepton particle family, participate in gravitational, electromagnetic and weak interactions. Electrons have quantum mechanical properties of both a particle and a wave, so they can collide with other particles and be diffracted like light. Since an electron is a fermion, no two electrons can occupy the same quantum state, a property known as the Pauli exclusion principle. The electron was identified as a particle in 1897 by J. J. Thomson and his team of British physicists. In many physical phenomena, such as electricity, magnetism, and thermal conductivity, electrons play an essential role. An electron generates a magnetic field while moving, and it is deflected by external magnetic fields. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. Electrons may be destroyed through annihilation with positrons, or may be absorbed during nucleosynthesis in stars. Electrons have many applications, including welding, cathode ray tubes, electron microscopes, radiation therapy, lasers and particle accelerators. (more...) Recently featured: Han Dynasty – Death Valley National Park – Wind