Editing Molecule (section)

== Bonding ==
Molecules are generally held together by [[covalent bonding]]. Several non-metallic elements exist only as molecules in the environment either in compounds or as homonuclear molecules, not as free atoms: for example, hydrogen.

While some people say a metallic crystal can be considered a single giant molecule held together by [[metallic bonding]],<ref>{{cite book |last1=Harry |first1=B. Gray |title=Chemical Bonds: An Introduction to Atomic and Molecular Structure |pages=210–211 |url=https://authors.library.caltech.edu/105209/15/TR000574_06_chapter-6.pdf |access-date=22 November 2021 |archive-date=31 March 2021 |archive-url=https://web.archive.org/web/20210331062040/https://authors.library.caltech.edu/105209/15/TR000574_06_chapter-6.pdf |url-status=live }}</ref> others point out that metals behave very differently than molecules.<ref>{{cite web |title=How many gold atoms make gold metal? |url=https://phys.org/news/2015-04-gold-atoms-metal.html |website=phys.org |access-date=22 November 2021 |language=en |archive-date=30 October 2020 |archive-url=https://web.archive.org/web/20201030202803/https://phys.org/news/2015-04-gold-atoms-metal.html |url-status=live }}</ref>

=== Covalent ===
[[File:Covalent bond hydrogen.svg|thumb|right|A covalent bond forming H<sub>2</sub> (right) where two [[hydrogen atom]]s share the two electrons]]
{{main|Covalent bonding}}
A covalent bond is a chemical bond that involves the sharing of [[electron pair]]s between atoms. These electron pairs are termed ''shared pairs'' or ''bonding pairs'', and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is termed ''covalent bonding''.<ref>{{cite book| author2= Brad Williamson| author3= Robin J. Heyden| last= Campbell| first= Neil A.| title= Biology: Exploring Life| url= http://www.phschool.com/el_marketing.html| access-date= 2012-02-05| year= 2006| publisher= [[Pearson Prentice Hall]]| location= Boston| isbn= 978-0-13-250882-7| archive-date= 2 November 2014| archive-url= https://web.archive.org/web/20141102041816/http://www.phschool.com/el_marketing.html| url-status= live}}</ref>

=== Ionic ===
{{main|Ionic bonding}} [[File:NaF.gif|thumb|left|[[Sodium]] and [[fluorine]] undergoing a redox reaction to form [[sodium fluoride]]. Sodium loses its outer [[electron]] to give it a stable [[electron configuration]], and this electron enters the fluorine atom [[exothermic]]ally.]]

Ionic bonding is a type of chemical bond that involves the [[electrostatic]] attraction between oppositely charged ions, and is the primary interaction occurring in [[ionic compound]]s. The ions are atoms that have lost one or more [[electron]]s (termed [[cation]]s) and atoms that have gained one or more electrons (termed [[anion]]s).<ref>{{Cite book|url=https://books.google.com/books?id=6VdROgeQ5M8C&q=ionic+bonding+-wikipedia&pg=PA7|title=Elements of Metallurgy and Engineering Alloys|last=Campbell|first=Flake C.|year=2008|publisher=[[ASM International]]|isbn=978-1-61503-058-3|language=en|access-date=27 October 2020|archive-date=31 March 2021|archive-url=https://web.archive.org/web/20210331062041/https://books.google.com/books?id=6VdROgeQ5M8C&q=ionic+bonding+-wikipedia&pg=PA7|url-status=live}}</ref> This transfer of electrons is termed ''electrovalence'' in contrast to [[covalent bond|covalence]]. In the simplest case, the cation is a [[metal]] atom and the anion is a [[Nonmetal (chemistry)|nonmetal]] atom, but these ions can be of a more complicated nature, e.g. molecular ions like NH<sub>4</sub><sup>+</sup> or SO<sub>4</sub><sup>2−</sup>. At normal temperatures and pressures, ionic bonding mostly creates solids (or occasionally liquids) without separate identifiable molecules, but the vaporization/sublimation of such materials does produce separate molecules where electrons are still transferred fully enough for the bonds to be considered ionic rather than covalent.
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