What is Electron?
An '''electron''' is a very small piece of [[matter]]. Its symbol is '''e<sup>−</sup>''', and it was discovered by [[J. J. Thomson]] in 1897. The electron is a [[subatomic particle]]. Every [[atom]] is made of some electrons that surround the [[Nucleus (physics)|nucleus]] of the atom. An electron can also be separate from any atom. It is believed to be an [[elementary particle]] because it cannot be broken down into anything smaller.<ref name=Purcell>Purcell, Edward M. 1985. ''Electricity and Magnetism''. Berkeley Physics Course Volume 2. McGraw-Hill. {{ISBN|0-07-004908-4}}.</ref> Its [[electric charge]] is negative.<ref>{{cite web|title=JERRY COFF|url=http://www.universetoday.com/73323/what-is-an-electron/|accessdate=10 September 2010}}</ref> Electrons have very little [[mass]] (little weight) so very little energy is needed to move them fast. They may move almost at the [[speed of light]], for instance, as [[beta particle]]s, and in the inner [[electron shell]]s of [[chemical element|elements]] with a large [[atomic number]]. <ref> US Dept. of Energy: [http://www.newton.dep.anl.gov/askasci/phy99/phy99092.htm] {{Webarchive|url=https://web.archive.org/web/20100530161022/http://www.newton.dep.anl.gov/askasci/phy99/phy99092.htm|date=2010-05-30}}</ref> Electrons take part in [[gravitation]]al, [[electromagnetic force|electromagnetic]] and [[weak interaction]]s.<ref name=Anastopoulos1>Anastopoulos, Charis 2008. ''Particle or Wave: the evolution of the concept of matter in modern physics''. Princeton University Press. pp261–262. {{ISBN|0691135126}}. https://books.google.com/books?id=rDEvQZhpltEC&pg=PA261</ref> The electromagnetic force is strongest in common situations. Electrons repel (push apart) from each other because they have the same electric charge. Electrons are attracted to protons because they have opposite electric charge. An electron has an [[electric field]], which describes these forces. The [[electricity]] that powers televisions, motors, mobile phones, basically everything (electric) is actually man