Electron: Difference between revisions
imported>John R. Brews (rewrite final paragraph) |
imported>John R. Brews (update links and values from revised NIST website) |
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An '''electron''' is an [[elementary particle]] that carries a negative [[elementary charge]] −''e''.<ref name=NIST0> | An '''electron''' is an [[elementary particle]] that carries a negative [[elementary charge]] −''e''.<ref name=NIST0> | ||
{{cite web |title=Elementary charge |url=http://physics.nist.gov/cgi-bin/cuu/Value?e|search_for=electron+charge |work=The NIST reference on constants, units, and uncertainty |publisher=[[National Institute of Standards and Technology]] |accessdate=2011- | {{cite web |title=Elementary charge |url=http://physics.nist.gov/cgi-bin/cuu/Value?e|search_for=electron+charge |work=The NIST reference on constants, units, and uncertainty |publisher=[[National Institute of Standards and Technology]] |accessdate=2011-09-04}} | ||
</ref> | </ref> | ||
::''e'' = 1.602 176 | ::''e'' = 1.602 176 565(35) × 10<sup>-19</sup> C | ||
It is a [[electron spin|spin-½]] [[lepton]] of mass<ref name=NIST1> | It is a [[electron spin|spin-½]] [[lepton]] of mass<ref name=NIST1> | ||
{{cite web |title=Electron mass |url=http://physics.nist.gov/cgi-bin/cuu/Value?me|search_for=electron+mass |work=The NIST reference on constants, units, and uncertainty |accessdate=2011- | {{cite web |title=Electron mass |url=http://physics.nist.gov/cgi-bin/cuu/Value?me|search_for=electron+mass |work=The NIST reference on constants, units, and uncertainty |accessdate=2011-09-04}} | ||
</ref> | </ref> | ||
::''m<sub>e</sub>''= 9.109 | ::''m<sub>e</sub>''= 9.109 382 91(40) × 10<sup>−31</sup> kg. | ||
It has a [[gyromagnetic ratio]]<ref name=NIST2> | It has a [[gyromagnetic ratio]]<ref name=NIST2> | ||
{{cite web |title=Electron gyromagnetic ratio |url=http://physics.nist.gov/cgi-bin/cuu/Value? | {{cite web |title=Electron gyromagnetic ratio |url=http://physics.nist.gov/cgi-bin/cuu/Value?gammae|search_for=gyromagnetic+ratio |work=The NIST reference on constants, units, and uncertainty |accessdate=2011-09-04}} | ||
</ref> | </ref> | ||
::''γ<sub>e</sub>'' = 1.760 859 | ::''γ<sub>e</sub>'' = 1.760 859 708(39) x 10<sup>11</sup> s<sup>-1</sup> T<sup>-1</sup> | ||
or a [[magnetic moment]] of about −1.00115965 Bohr magneton (''μ<sub>B</sub>''):<ref name=NIST4> | or a [[magnetic moment]] of about −1.00115965 Bohr magneton (''μ<sub>B</sub>''):<ref name=NIST4> | ||
{{cite web |title=Bohr magneton |url=http://physics.nist.gov/cgi-bin/cuu/Value? | {{cite web |title=Bohr magneton |url=http://physics.nist.gov/cgi-bin/cuu/Value?mub|search_for=Bohr+magneton |work=The NIST reference on constants, units, and uncertainty |accessdate=2011-09-04}} | ||
</ref> | </ref> | ||
::''μ<sub>B</sub>'' = 927.400 | ::''μ<sub>B</sub>'' = 927.400 968(20) x 10<sup>-26</sup> J/ T. | ||
Together with [[neutron]]s and [[proton]]s in atomic [[nucleus (physics)|nuclei]], electrons constitute [[atom]]s and [[molecule]]s. The (quantum mechanical) interaction between electrons on nearby atoms underlies the [[chemical bonding]] in molecules, gases, liquids and solids, such as [[crystals]]. The statistical behavior of large numbers of electrons is governed by the [[Fermi function]]. | Together with [[neutron]]s and [[proton]]s in atomic [[nucleus (physics)|nuclei]], electrons constitute [[atom]]s and [[molecule]]s. The (quantum mechanical) interaction between electrons on nearby atoms underlies the [[chemical bonding]] in molecules, gases, liquids and solids, such as [[crystals]]. The statistical behavior of large numbers of electrons is governed by the [[Fermi function]]. | ||
Revision as of 12:00, 4 September 2011
An electron is an elementary particle that carries a negative elementary charge −e.[1]
- e = 1.602 176 565(35) × 10-19 C
It is a spin-½ lepton of mass[2]
- me= 9.109 382 91(40) × 10−31 kg.
It has a gyromagnetic ratio[3]
- γe = 1.760 859 708(39) x 1011 s-1 T-1
or a magnetic moment of about −1.00115965 Bohr magneton (μB):[4]
- μB = 927.400 968(20) x 10-26 J/ T.
Together with neutrons and protons in atomic nuclei, electrons constitute atoms and molecules. The (quantum mechanical) interaction between electrons on nearby atoms underlies the chemical bonding in molecules, gases, liquids and solids, such as crystals. The statistical behavior of large numbers of electrons is governed by the Fermi function.
The behavior of electrons at the microscopic level of individual particles or atoms must be described by quantum mechanics or quantum electrodynamics. On a larger scale, however, these microscopic considerations often can be approximated as macroscopic currents and charges, which then are used in classical electrodynamics to describe electromagnetic fields using the (classical) Maxwell equations. In such an approach, quantum mechanics can be used to establish the electronic properties of materials, which then are expressed in the macroscopic Maxwell equations by introducing material parameters such as permittivities, permeabilities, conductivities and the like without further need for quantum theory.
References
- ↑ Elementary charge. The NIST reference on constants, units, and uncertainty. National Institute of Standards and Technology. Retrieved on 2011-09-04.
- ↑ Electron mass. The NIST reference on constants, units, and uncertainty. Retrieved on 2011-09-04.
- ↑ Electron gyromagnetic ratio. The NIST reference on constants, units, and uncertainty. Retrieved on 2011-09-04.
- ↑ Bohr magneton. The NIST reference on constants, units, and uncertainty. Retrieved on 2011-09-04.