How many valence electrons are in an atom of phosphorus? a. 2 b. 3 c. 4 d. 5Note:
Field emission (FE) (also known as field electron emission and electron field emission) is emission of electrons induced by an electrostatic field. The most common context is FE from a solid surface into vacuum. [ However, FE can take place from solid or liquid surfaces, into vacuum, air, a fluid, or any non-conducting or weakly conducting dielectric. The field-induced promotion of electrons from the valence to conduction band of semiconductors (the Zener effect) can also be regarded as a form of FE. The terminology is historical because related phenomena of surface photoeffect, thermionic emission or Richardson-Dushman effect and "cold electronic emission", i.e. the emission of electrons in strong static (or quasi-static) electric fields, were discovered and studied independently from 1880s to 1930s. When field emission is used without qualifiers it typically means "cold emission."
Field emission in pure metals occurs in high electric fields: the gradients are typically higher than 1 gigavolt per metre and strongly dependent upon the work function. Electron sources based on field emission have a number of applications, but it is most commonly an undesirable primary source of vacuum breakdown and electrical discharge phenomena, which engineers work to prevent. Examples of applications for surface field emission include construction of bright electron sources for high-resolution electron microscopes or to discharge spacecraft from induced charges. Devices which eliminate induced charges are termed charge-neutralizers.
Field emission was explained by quantum tunneling of electrons in the late 1920s. This was one of the triumphs of the nascent quantum mechanics. The theory of field emission from bulk metals was proposed by Ralph H. Fowler and Lothar Wolfgang Nordheim. A family of approximate equations, "Fowler?Nordheim equations", is named after them. ] Auto answered|Score .4973|Pinkblush|Points 13|Note:
I'm sorry that that wasn't a good answer. Please hold on while I contact an expert.Weegy:
The number of valance electrons any atom has can be found by looking at the group number at the top of the column the atom is in. [ Except for the transition metals (groups 3-12), single digit groups give the valence electrons, for double digit group numbers (groups 13-18), take the second of the two digits as the number of valence electrons. The transition elements usually have 2 but some in groups 6 and 11 have only 1.
So as the first responder noted, phosphorus in group 15 on the periodic table (a two digit group number) has 5 valence electrons.
] Expert answered|cecillereign|Points 10|
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