AskDefine | Define electrons

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Noun

electrons
  1. Plural of 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

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