The Physics Factbook™
Edited by Glenn Elert -- Written by his students
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|Bibliographic Entry||Result |
|World Book Encyclopedia. Chicago: World Book.||"The diameter of an electron is less than 1/1000 the diameter of a proton. A proton has a diameter of approximately 1/25,000,000,000,000 inch (0.000000000001 mm)."||< 10-18 m|
|Mac Gregor, Malcolm H. The Enigmatic Electron. Boston: Klurer Academic, 1992: 4-5.||"Rc = 3.86 × 10-11 cm |
Rqmc = 6.64 × 10-11 cm
Rqmc = 6.70 × 10-11 cm"
|4–7 × 10-13 m|
|Pauling, Linus. College Chemistry. San Francisco: Freeman, 1964: 57, 4-5.||"The radius of the electron has not been determined exactly but it is known to be less than 1 × 10-13 cm"||< 10-15 m|
|"Ro = 2.82 × 10-13 cm"||2.82 × 10-15 m|
An electron is a negatively charged subatomic particle. They are responsiblefor the formation of chemical compounds. Electrons are considered to be fundamentalunits of matter (they are not made up of smaller units). Although scientists havebeen studying electrons for quite a while, the exact diameter of an electron isunknown. According to Malcolm H. Mac Gregor,
The electron is a point-like particle-that is, a particle with no measurable dimensions, at least within the limitations of present-day instrumentation. However, a rather compelling case can be made for an opposing viewpoint: namely, that the electron is in fact a large particle which contains an embedded point-like charge.
The electron was the first subatomic particle to be discovered. It was discoveredin 1897 by a British physicist named Sir Joseph John Thomson. Later, in 1913,an American Physicist by the name of Robert A. Millikan obtained an accurate measurementof the electron's charge. Recent studies show that the charge of an electron is1.60218 × 10-19 coulombs. The mass of an electron is knownto be 9.10939 × 10-31 kilograms.
In all neutral atoms there are the same number of electrons as protons. Electronsare bound to the nucleus by electrostatic forces. Most of the volume of an atomis occupied by electrons, even though they barley contribute to the atomic mass.Neils Bohr, Wolfgang Pauli, and others discovered the pattern in which electronsare distributed throughout an atom in the 1920s. Electrons are arranged at variousdistances from the nucleus, and are arranged in energy levels called shells. Theaverage distance of outer electrons from the nucleus is a few tens of nanometersin all atoms. In heavy atoms inner electrons are much closer to the nucleus. Thenumber of electrons in outermost shell determines the chemical behavior of thatatom. If an atom combines with another atom to form a molecule, than the electronsin the outermost shell are transferred from one atom to another or shared betweenatoms.
Danny Donohue -- 2000
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