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The electron is a subatomic particle, symbol or , with a negative elementary electric charge.〔(【引用サイトリンク】url=http://www.universetoday.com/73323/what-is-an-electron/ )〕 Electrons belong to the first generation of the lepton particle family,〔 and are generally thought to be elementary particles because they have no known components or substructure.〔 The electron has a mass that is approximately 1/1836 that of the proton.〔 Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value in units of ''ħ'', which means that it is a fermion. Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle.〔 Like all matter, electrons have properties of both particles and waves, and so can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a higher De Broglie wavelength for typical energies. Many physical phenomena involve electrons in an essential role, such as electricity, magnetism, and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions.〔 An electron generates an electric field surrounding it. An electron moving relative to an observer generates a magnetic field. External magnetic fields deflect an electron. Electrons radiate or absorb energy in the form of photons when accelerated. Laboratory instruments are capable of containing and observing individual electrons as well as electron plasma using electromagnetic fields, whereas dedicated telescopes can detect electron plasma in outer space. Electrons have many applications, including electronics, welding, cathode ray tubes, electron microscopes, radiation therapy, lasers, gaseous ionization detectors and particle accelerators. Interactions involving electrons and other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between positive protons inside atomic nuclei and negative electrons composes atoms. Ionization or changes in the proportions of particles changes the binding energy of the system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding.〔 British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms in 1838;〔 Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897.〔〔Dahl (1997:122–185).〕〔 Electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons may be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron except that it carries electrical and other charges of the opposite sign. When an electron collides with a positron, both particles may be totally annihilated, producing gamma ray photons. ==History== The ancient Greeks noticed that amber attracted small objects when rubbed with fur. Along with lightning, this phenomenon is one of humanity's earliest recorded experiences with electricity. 〔 In his 1600 treatise ラテン語:''De Magnete'', the English scientist William Gilbert coined the New Latin term ラテン語:''electricus'', to refer to this property of attracting small objects after being rubbed. 〔 Both ''electric'' and ''electricity'' are derived from the Latin ''ラテン語:ēlectrum'' (also the root of the alloy of the same name), which came from the Greek word for amber, ('). In the early 1700s, Francis Hauksbee and French chemist Charles François de Fay independently discovered what they believed were two kinds of frictional electricity—one generated from rubbing glass, the other from rubbing resin. From this, Du Fay theorized that electricity consists of two electrical fluids, ''vitreous'' and ''resinous'', that are separated by friction, and that neutralize each other when combined.〔 〕 A decade later Benjamin Franklin proposed that electricity was not from different types of electrical fluid, but the same electrical fluid under different pressures. He gave them the modern charge nomenclature of positive and negative respectively.〔 〕 Franklin thought of the charge carrier as being positive, but he did not correctly identify which situation was a surplus of the charge carrier, and which situation was a deficit.〔 〕 Between 1838 and 1851, British natural philosopher Richard Laming developed the idea that an atom is composed of a core of matter surrounded by subatomic particles that had unit electric charges.〔 〕 Beginning in 1846, German physicist William Weber theorized that electricity was composed of positively and negatively charged fluids, and their interaction was governed by the inverse square law. After studying the phenomenon of electrolysis in 1874, Irish physicist George Johnstone Stoney suggested that there existed a "single definite quantity of electricity", the charge of a monovalent ion. He was able to estimate the value of this elementary charge ''e'' by means of Faraday's laws of electrolysis.〔 〕 However, Stoney believed these charges were permanently attached to atoms and could not be removed. In 1881, German physicist Hermann von Helmholtz argued that both positive and negative charges were divided into elementary parts, each of which "behaves like atoms of electricity".〔 〕 Stoney initially coined the term ''electrolion'' in 1881. Ten years later, he switched to ''electron'' to describe these elementary charges, writing in 1894: "... 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''". A 1906 proposal to change to ''electrion'' failed because Hendrik Lorentz preferred to keep ''electron''.〔 〕〔 〕 The word ''electron'' is a combination of the words ''electric'' and ''ion''.〔"electron, n.2". OED Online. March 2013. Oxford University Press. Accessed 12 April 2013 ()〕 The suffix -''on'' which is now used to designate other subatomic particles, such as a proton or neutron, is in turn derived from electron.〔 〕〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electron」の詳細全文を読む スポンサード リンク
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