The Electron reference article from the English Wikipedia on 24-Jul-2004
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Electron

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Electron
Helium atom (not to scale)

The electrons move rapidly around the nucleus.
Classification
Elementary particle
Fermion
Lepton
First Generation
Electron

Properties
Mass: 9.10 × 10-31 kg
Electric Charge: -1.6 × 10-19C
Spin: 1/2
Color Charge: none
Interaction: Gravity, Electromagnetic,Weak

The electron (also called negatron, commonly represented as e) is a subatomic particle. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration.

The electron is one of a class of subatomic particles called leptons which are believed to be fundamental particles (that is, they cannot be broken down into smaller constituent parts).

The electron has spin 1/2, which implies it is a fermion, i.e., follows the Fermi-Dirac statistics.

In quantum mechanics, the electron is described by the Dirac Equation. In the Standard Model of particle physics, it forms a doublet in SU(2) with the electron neutrino, as they interact through the weak interaction. The electron has two more massive partners, with the same charge but different masses: the muon and the tauon.

The antimatter counterpart of the electron is its antiparticle, the positron. The positron has the same amount of electrical charge as the electron, except that the charge is positive. It has the same mass and spin as the electron. When an electron and a positron meet, they may annihilate each other, giving rise to two gamma-ray photons, each having an energy of 0.511 MeV (511 keV). See also Electron-positron annihilation.

Some theorists believe the electron may be a very small black hole.

Table of contents
1 Dual nature
2 Details
3 Electricity
4 History
5 See also
6 External links

Dual nature

Electrons can exhibit properties of both particles and waves. An electron bound to a nucleus behaves as a standing wave.

Details

The electron has a negative electric charge of -1.6 × 10-19 coulombs, and a mass of about 9.10 × 10-31 kg (0.51 MeV/c2), which is 1/1800 of the proton mass.

It is believed that the number of electrons that would fit in the known universe is 10 followed by 130 zeros.

Electricity

When electrons move, free of the nuclei of atoms, and there is a net flow, this flow is called electricity, or an electric current. This might be compared to a flock of sheep moving north together, while the shepherds do not. Electric charge can be directly measured with an electrometer. Electric current can be directly measured with a galvanometer.

So-called "static electricity" is not a flow of electrons at all. More correctly called a "static charge", it refers to a body that has more or fewer electrons than are required to balance the positive charge of the nuclei. When there is an excess of electrons, the object is said to be "negatively charged". When there are fewer electrons than protons, the object is said to be "positively charged". When the number of electrons and the number of protons are equal, the object is said to be electrically "neutral".

History

The electron had been posited by G. Johnstone Stoney, as a unit of charge in electrochemistry, but Thompson realised that it was also a subatomic particle.

The electron was discovereded by J.J. Thomson in 1897 at the Cavendish Laboratory at Cambridge University, while studying "cathode rays." Influenced by the work of James Clerk Maxwell, and the discovery of the X-ray, he deduced that cathode rayss existed and were negatively charged "particles", which he called "corpuscles".

See also

External links