User Contributed Dictionary
Noun
electrons- 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
- The NIST’s latest CODATA value for electron mass
- The Discovery of the Electron from the American Institute of Physics History Center
- Particle Data Group
- Stoney, G. Johnstone, "Of the 'Electron,' or Atom of Electricity". Philosophical Magazine. Series 5, Volume 38, p. 418-420 October 1894.
- Eric Weisstein's World of Physics: Electron
- Researchers Catch Motion of a Single Electron on Video
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