electron, elementary particle elementary particles, the most basic physical constituents of the universe.

Basic Constituents of Matter

Molecules are built up from the atom , which is the basic unit of any chemical element .
..... Click the link for more information. carrying a unit charge of negative electricity. Ordinary electric current is the flow of electrons through a wire conductor (see electricity electricity, class of phenomena arising from the existence of charge . The basic unit of charge is that on the proton or electron —the proton's charge is designated as positive while the electron's is negative.
..... Click the link for more information. ). The electron is one of the basic constituents of matter. An atom atom [Gr.,=uncuttable (indivisible)], basic unit of matter ; more properly, the smallest unit of a chemical element having the properties of that element.

Structure of the Atom

..... Click the link for more information. consists of a small, dense, positively charged nucleus surrounded by electrons that whirl about it in orbits, forming a cloud of charge. Ordinarily there are just enough negative electrons to balance the positive charge of the nucleus, and the atom is neutral. If electrons are added or removed, a net charge results, and the atom is said to be ionized (see ion ion, atom or group of atoms having a net electric charge .

Positive and Negative Electric Charges

A neutral atom or group of atoms becomes an ion by gaining or losing one or more electrons or protons.
..... Click the link for more information. ). Atomic electrons are responsible for the chemical properties of matter (see valence valence, combining capacity of an atom expressed as the number of single bonds the atom can form or the number of electrons an element gives up or accepts when reacting to form a compound.
..... Click the link for more information. ). The name electron was first used for a unit of negative electricity by the English physicist G. J. Stoney in the late 19th cent. The actual discovery of the particle, however, was made in 1897 by J. J. Thomson, who showed that cathode rays are composed of electrons and who measured the ratio of charge to mass for the electron. In 1909, R. A. Millikan measured the charge of the electron. Combining these two results gives the mass of the electron (about 1/1,840 of the mass of the proton). Ernest Rutherford, in 1903, showed that beta rays (see radioactivity radioactivity, spontaneous disintegration or decay of the nucleus of an atom by emission of particles, usually accompanied by electromagnetic radiation . The energy produced by radioactivity has important military and industrial applications.
..... Click the link for more information. ) are high-energy electrons. In 1927, Davisson and Germer, working with high-speed electron beams, discovered that electrons sometimes exhibit the wave property of diffraction. This confirmed L. V. de Broglie's hypothesis that electrons, which had previously been thought of as particles, also possess certain wave properties (see quantum theory quantum theory, modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics.
..... Click the link for more information. ). The wavelike properties of electrons are utilized in the electron microscope microscope, optical instrument used to increase the apparent size of an object.

Simple Microscopes

A magnifying glass, an ordinary double convex lens having a short focal length, is a simple microscope.
..... Click the link for more information. and other devices. The electron is the lightest particle having a non-zero rest mass. It belongs to the lepton lepton (lĕp`tŏn') [Gr.,=light (i.e.
..... Click the link for more information. class of particles and, together with its antiparticle antimatter, composed of atoms made up of antiprotons and antineutrons in a nucleus surrounded by positrons. A very simple type of "atom" incorporating antiparticles is positronium, a brief pairing of a positron and an electron that may occur before their annihilation.
..... Click the link for more information. , the positron, and its associated neutrino neutrino (n

trē`nō) [Ital.
..... Click the link for more information. and antineutrino, constitutes a subfamily of the leptons. In any particle reaction involving any of the four members of the electron family, the total electron family number (+1 for ordinary particles, −1 for antiparticles) must be conserved (see conservation laws conservation laws, in physics, basic laws that together determine which processes can or cannot occur in nature; each law maintains that the total value of the quantity governed by that law, e.g., mass or energy, remains unchanged during physical processes.
..... Click the link for more information. , in physics). As a consequence, an electron and a positron (total electron family number equals zero) can annihilate each other to yield two or more photons or a neutrino-antineutrino pair, but not two neutrinos (total electron family number equals two).

electron

Lightest electrically charged subatomic particle known. It carries a negative charge (see electric charge), the basic charge of electricity. An electron has a small mass, less than 0.1% the mass of an atom. Under normal circumstances, electrons move about the nucleus of an atom in orbitals that form an electron cloud bound in varying strengths to the positively charged nucleus. Electrons closer to the nucleus are held more tightly. The first subatomic particle discovered, the electron was identified in 1897 by J. J. Thomson.

An elementary particle that circles the nucleus of an atom. Electrons are considered to be negatively charged. See wave-particle duality and photon.

(electronics)

electron - A sub-atomic particle with a negative quantised charge. A flow of electrical current consists of the unidirectional (on average) movement of many electrons. The more mobile electrons are in a given material, the greater it electrical conductance (or equivalently, the lower its resistance).