Electron

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An electron is a very small piece of matter and energy. Its symbol is e.

The electron is a subatomic particle. It is believed to be an elementary particle because it cannot be broken down into anything smaller.[1] It is negatively charged,[2] and may move almost at the speed of light.[3]

Electrons take part in gravitational, electromagnetic and weak interactions.[4] The electricity that powers radios, motors, and many other things consists of many electrons moving through wires or other conductors.

Description[change | change source]

The Niels Bohr model of the atom. Three electron shells about a nucleus, with an electron moving from the second to the first level and releasing a photon.

Electrons have the smallest electrical charge. This electrical charge equals the charge of a proton, but has the opposite sign. For this reason, electrons are attracted by the protons of atomic nuclei and usually form atoms. An electron has a mass of about 1/1836 times a proton.Closing </ref> missing for <ref> tag

Measurement[change | change source]

Electric charge can be directly measured with a device called an electrometer. Electric current can be directly measured with a galvanometer. The measurement given off by a galvanometer is different from the measurement given off by an electrometer. Today laboratory instruments are capable of containing and observing individual electrons.

'Seeing' an electron[change | change source]

In laboratory conditions, the interactions of individual electrons can be observed by means of particle detectors, which allow measurement of specific properties such as energy, spin and charge.[5] In one instance a Penning trap was used to contain a single electron for 10 months.[6] The magnetic moment of the electron was measured to a precision of eleven digits, which, in 1980, was a greater accuracy than for any other physical constant.[7]

The first video images of an electron's energy distribution were captured by a team at Lund University in Sweden, February 2008. The scientists used extremely short flashes of light, called attosecond pulses, which allowed an electron's motion to be observed for the first time.[8][9] The distribution of the electrons in solid materials can also be visualized.[10]

Anti-particle[change | change source]

The antiparticle of the electron is called a positron. This is identical to the electron, but carries electrical and other charges of the opposite sign. When an electron collides with a positron, they may scatter off each other or be totally annihilated, producing a pair (or more) of gamma ray photons.

History of its discovery[change | change source]

The effects of electrons were known long before it could be explained. The Ancient Greeks knew that rubbing amber against fur attracted small objects. Now we know the rubbing strips off electrons, and that gives an electric charge to the amber. Many physicists worked on the electron. J.J. Thomson proved it existed,[11] in 1897, but another man gave it the name 'electron'.[12]

The electron cloud model[change | change source]

The model views electrons as holding indeterminate positions in a diffuse cloud around the nucleus of the atom.

The uncertainty principle prevents simultaneous knowledge of an electron's position and energy level. These potential states form a cloud around the atom. The potential states of electrons in a single atom form a single, uniform cloud.

Related pages[change | change source]

References[change | change source]

  1. Purcell, Edward M. 1985. Electricity and Magnetism. Berkeley Physics Course Volume 2. McGraw-Hill. ISBN 0-07-004908-4.
  2. "JERRY COFF". http://www.universetoday.com/73323/what-is-an-electron/. Retrieved 10 September 2010.
  3. For instance, as beta particles, and in the inner electron shells of elements with a large atomic number. US Dept. of Energy: [1]
  4. Anastopoulos, Charis 2008. Particle or Wave: the evolution of the concept of matter in modern physics. Princeton University Press. pp261–262. ISBN 0691135126. http://books.google.com/?id=rDEvQZhpltEC&pg=PA261.
  5. Grupen, Claus 1999. "Physics of Particle Detection". AIP Conference Proceedings, Instrumentation in Elementary Particle Physics, VIII. 536. Istanbul: Dordrecht, D. Reidel Publishing Company. pp. 3–34. doi:10.1063/1.1361756.
  6. Staff (2008). "The Nobel Prize in Physics 1989". The Nobel Foundation. http://nobelprize.org/nobel_prizes/physics/laureates/1989/illpres/. Retrieved 2008-09-24.
  7. Ekstrom, Philip (1980). "The isolated Electron" (PDF). Scientific American 243 (2): 91–101. http://tf.nist.gov/general/pdf/166.pdf. Retrieved 2008-09-24.
  8. Mauritsson, Johan. "Electron filmed for the first time ever" (PDF). Lunds Universitet. http://www.atto.fysik.lth.se/video/pressrelen.pdf. Retrieved 2008-09-17.
  9. Mauritsson, J.; Johnsson, P.; Mansten, E.; Swoboda, M.; Ruchon, T.; L’huillier, A.; Schafer, K. J. (2008). "Coherent Electron Scattering Captured by an Attosecond Quantum Stroboscope" (pdf). Physical Review Letters 100: 073003. doi:10.1103/PhysRevLett.100.073003. http://www.atto.fysik.lth.se/publications/papers/MauritssonPRL2008.pdf.
  10. Damascelli, Andrea (2004). "Probing the electronic structure of complex systems by ARPES". Physica Scripta T109: 61–74. doi:10.1238/Physica.Topical.109a00061.
  11. Davis & Falconer, J.J. Thomson and the Discovery of the Electron
  12. Shipley, Joseph T. 1945. Dictionary of word origins. The Philosophical Library. p133.

Other websites[change | change source]

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