Editing Chemistry (section)

===Bonding===
{{Main|Chemical bond}}
[[File:Ionic bonding animation.gif|thumb|right|upright=1.15|An animation of the process of ionic bonding between [[sodium]] (Na) and [[chlorine]] (Cl) to form [[sodium chloride]], or common table salt. Ionic bonding involves one atom taking valence electrons from another (as opposed to sharing, which occurs in covalent bonding).]]

Atoms sticking together in molecules or crystals are said to be bonded with one another. A chemical bond may be visualized as the [[multipole]] balance between the positive charges in the nuclei and the negative charges oscillating about them.<ref>{{cite web |author= |title=Chemical Bonding by Anthony Carpi, PhD |url=http://www.visionlearning.com/library/module_viewer.php?mid=55 |url-status=live |archive-url=https://web.archive.org/web/20110717215216/http://www.visionlearning.com/library/module_viewer.php?mid=55 |archive-date=17 July 2011 |access-date=12 June 2011 |publisher=visionlearning}}</ref> More than simple attraction and repulsion, the energies and distributions characterize the availability of an electron to bond to another atom.

The chemical bond can be a [[covalent bond]], an [[ionic bond]], a [[hydrogen bond]] or just because of [[Van der Waals force]]. Each of these kinds of bonds is ascribed to some potential. These potentials create the interactions which hold atoms together in [[molecule]]s or [[crystal]]s. In many simple compounds, [[valence bond theory]], the Valence Shell Electron Pair Repulsion model ([[VSEPR]]), and the concept of [[oxidation number]] can be used to explain molecular structure and composition.

An ionic bond is formed when a metal loses one or more of its electrons, becoming a positively charged cation, and the electrons are then gained by the non-metal atom, becoming a negatively charged anion. The two oppositely charged ions attract one another, and the ionic bond is the electrostatic force of attraction between them. For example, [[sodium]] (Na), a metal, loses one electron to become an Na<sup>+</sup> cation while [[chlorine]] (Cl), a non-metal, gains this electron to become [[Chloride|Cl<sup>−</sup>]]. The ions are held together due to electrostatic attraction, and that compound [[sodium chloride]] (NaCl), or common table salt, is formed.

[[File:Elektronenformel Punkte CH4.svg|thumb|upright=0.75|left|In the [[methane]] molecule (CH<sub>4</sub>), the carbon atom shares a pair of valence electrons with each of the four hydrogen atoms. Thus, the octet rule is satisfied for C-atom (it has eight electrons in its valence shell) and the duet rule is satisfied for the H-atoms (they have two electrons in their valence shells).]]
In a covalent bond, one or more pairs of [[valence electron]]s are shared by two atoms: the resulting electrically neutral group of bonded atoms is termed a [[molecule]]. Atoms will share valence electrons in such a way as to create a [[noble gas]] electron configuration (eight electrons in their outermost shell) for each atom. Atoms that tend to combine in such a way that they each have eight electrons in their valence shell are said to follow the [[octet rule]]. However, some elements like [[hydrogen]] and [[lithium]] need only two electrons in their outermost shell to attain this stable configuration; these atoms are said to follow the ''duet rule'', and in this way they are reaching the electron configuration of the noble gas [[helium]], which has two electrons in its outer shell.

Similarly, theories from [[classical physics]] can be used to predict many ionic structures. With more complicated compounds, such as [[complex (chemistry)|metal complexes]], valence bond theory is less applicable and alternative approaches, such as the [[molecular orbital]] theory, are generally used.