AskDefine | Define electron

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Dictionary Definition

electron n : an elementary particle with negative charge [syn: negatron]

User Contributed Dictionary

English

Etymology

From sc=Grek from sc=Grek. See also electric + -on.

Pronunciation

Noun

  1. The subatomic particle having a negative charge and orbiting the nucleus; the flow of electrons in a conductor constitutes electricity.
  2. In the context of "chemistry|obsolete": An alloy of magnesium and aluminum.

Related terms

Translations

the negatively charged subatomic particles that orbit atoms

See also

Interlingua

Noun

ia-noun es
  1. electron

Romanian

Noun

  1. electron

Extensive Definition

The electron is a fundamental subatomic particle that carries a negative electric charge. It is a spin ½ lepton that participates in electromagnetic interactions, and its mass is approximately 1/1836 of that of the proton. Together with atomic nuclei, which consist of protons and neutrons, electrons make up atoms. Their interaction with adjacent nuclei is the main cause of chemical bonding.

History

The name electron comes from the Greek word for amber, ήλεκτρον. This material played an essential role in the discovery of electrical phenomena. The ancient Greeks knew, for example, that rubbing a piece of amber with fur left an electric charge on its surface, which could then create a spark when brought close to a grounded object. For more about the history of the term electricity, see History of electricity.
The electron as a unit of charge in electrochemistry was posited by G. Johnstone Stoney in 1874, who also coined the term electron in 1894.
1=In this paper an estimate was made of the actual amount of this most remarkable fundamental unit of electricity, for which I have since ventured to suggest the name electron.2=
During the late 1890s a number of physicists posited that electricity could be conceived of as being made of discrete units, which were given a variety of names, but the reality of these units had not been confirmed in a compelling way.
The discovery that the electron was a subatomic particle was made in 1897 by J.J. Thomson at the Cavendish Laboratory at Cambridge University, while he was studying cathode ray tubes. A cathode ray tube is a sealed glass cylinder in which two electrodes are separated by a vacuum. When a voltage is applied across the electrodes, cathode rays are generated, causing the tube to glow. Through experimentation, Thomson discovered that the negative charge could not be separated from the rays (by the application of magnetism), and that the rays could be deflected by an electric field. He concluded that these rays, rather than being waves, were composed of negatively charged particles he called "corpuscles". He measured their mass-to-charge ratio and found it to be over a thousand times smaller than that of a hydrogen ion, suggesting that they were either very highly charged or very small in mass. Later experiments by other scientists upheld the latter conclusion. Their mass-to-charge ratio was also independent of the choice of cathode material and the gas originally in the vacuum tube. This led Thomson to conclude that they were universal among all materials.
The electron's charge was carefully measured by R. A. Millikan in his oil-drop experiment of 1909.
The periodic law states that the chemical properties of elements largely repeat themselves periodically and is the foundation of the periodic table of elements. The law itself was initially explained by the atomic mass of the element. However, as there were anomalies in the periodic table, efforts were made to find a better explanation for it. In 1913, Henry Moseley introduced the concept of the atomic number and explained the periodic law in terms of the number of protons each element has. In the same year, Niels Bohr showed that electrons are the actual foundation of the table. In 1916, Gilbert Newton Lewis explained the chemical bonding of elements by electronic interactions.

Classification

The electron is in the class of subatomic particles called leptons, which are believed to be fundamental particles.
As with all particles, electrons can also act as waves. This is called the wave-particle duality, also known by the term complementarity coined by Niels Bohr, and can be demonstrated using the double-slit experiment.
The antiparticle of an electron is the positron, which has positive rather than negative charge. The discoverer of the positron, Carl D. Anderson, proposed calling standard electrons negatrons, and using electron as a generic term to describe both the positively and negatively charged variants. This usage of the term "negatron" is still occasionally encountered today, and it may also be shortened to "negaton".

Properties and behavior

Electrons have an electric charge of −1.602 × 10−19 C, a mass of 9.11 × 10−31 kg based on charge/mass measurements equivalent to a rest mass of about 0.511 MeV/c². The mass of the electron is approximately 1/1836 of the mass of the proton. The common electron symbol is e−.
In the Standard Model of particle physics, the electron is the first-generation charged lepton. It forms a weak isospin doublet with the electron neutrino; these two particles interact with each other through both the charged and neutral current weak interaction. The electron is very similar to the two more massive particles of higher generations, the muon and the tau lepton, which are identical in charge, spin, and interaction, but differ in mass.
The antimatter counterpart of the electron is 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 emitted at roughly 180° to each other. If the electron and positron had negligible momentum, each gamma ray will have an energy of 0.511 MeV. See also Electron-positron annihilation.
Electrons are a key element in electromagnetism, a theory that is accurate for macroscopic systems, and for classical modelling of microscopic systems.

Notes

See also

External links

electron in Afrikaans: Elektron
electron in Arabic: إلكترون
electron in Asturian: Electrón
electron in Azerbaijani: Elektron
electron in Bengali: ইলেকট্রন
electron in Min Nan: Tiān-chú
electron in Bosnian: Elektron
electron in Breton: Elektron
electron in Bulgarian: Електрон
electron in Catalan: Electró
electron in Chuvash: Электрон
electron in Czech: Elektron
electron in Welsh: Electron
electron in Danish: Elektron
electron in German: Elektron
electron in Estonian: Elektron
electron in Modern Greek (1453-): Ηλεκτρόνιο
electron in Spanish: Electrón
electron in Esperanto: Elektrono
electron in Basque: Elektroi
electron in Persian: الکترون
electron in French: Électron
electron in Irish: Leictreon
electron in Galician: Electrón
electron in Korean: 전자
electron in Hindi: विद्युद्णु
electron in Croatian: Elektron
electron in Ido: Elektrono
electron in Indonesian: Elektron
electron in Interlingua (International Auxiliary Language Association): Electron
electron in Icelandic: Rafeind
electron in Italian: Elettrone
electron in Hebrew: אלקטרון
electron in Kannada: ಎಲೆಕ್ಟ್ರಾನ್
electron in Georgian: ელექტრონი
electron in Swahili (macrolanguage): Elektroni
electron in Kurdish: Kareva
electron in Latin: Electron
electron in Latvian: Elektrons
electron in Lithuanian: Elektronas
electron in Lingala: Eléktron
electron in Lojban: dutydikca kantu
electron in Lombard: Elettron
electron in Hungarian: Elektron
electron in Macedonian: Електрон
electron in Malayalam: ഇലക്ട്രോണ്‍
electron in Marathi: विजाणू
electron in Malay (macrolanguage): Elektron
electron in Mongolian: Электрон
electron in Dutch: Elektron
electron in Japanese: 電子
electron in Norwegian: Elektron
electron in Norwegian Nynorsk: Elektron
electron in Novial: Elektrone
electron in Occitan (post 1500): Electron
electron in Uzbek: Elektron
electron in Low German: Elektron
electron in Polish: Elektron
electron in Portuguese: Elétron
electron in Kölsch: Elektron
electron in Romanian: Electron
electron in Quechua: Iliktrun
electron in Russian: Электрон
electron in Saterfriesisch: Elektron
electron in Albanian: Elektroni
electron in Sicilian: Elettroni
electron in Simple English: Electron
electron in Sindhi: برقيو
electron in Slovak: Elektrón
electron in Slovenian: Elektron
electron in Serbian: Електрон
electron in Sundanese: Éléktron
electron in Finnish: Elektroni
electron in Swedish: Elektron
electron in Tamil: எதிர்மின்னி
electron in Telugu: ఎలక్ట్రాన్
electron in Thai: อิเล็กตรอน
electron in Vietnamese: Điện tử
electron in Turkish: Elektron
electron in Buginese: Elektron
electron in Ukrainian: Електрон
electron in Urdu: برقیہ
electron in Venetian: Ełetron
electron in Yoruba: Atanná
electron in Contenese: 電子
electron in Samogitian: Elektruons
electron in Chinese: 电子

Synonyms, Antonyms and Related Words

Kern, NMR, alpha particle, antibaryon, antilepton, antimeson, atom, atomic nucleus, atomic particle, baryon, beta particle, cathode particle, electron affinity, electron cloud, electron pair, electron shells, electron spin, electron transfer, electron-positron pair, elementary particle, energy level, excited state, extranuclear electrons, ground state, ion, lepton, lone pair, meson, molecule, monad, negatron, neutron, nuclear force, nuclear magnetic resonance, nuclear particle, nuclear resonance, nucleon, nucleosynthesis, nucleus, octet, orbital electron, photoelectron, photon, proton, quark, recoil electron, secondary electron, shared pair, strangeness, strong interaction, subvalent electrons, surface-bound electron, thermion, triton, valence electron, valence electrons, valence shell, wandering electron
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