Delocalized electron 653183 216294073 2008-06-01T00:18:41Z SmackBot 433328 Date the maintenance tags or general fixes {{Unreferenced|date=May 2008}} [[Image:Benz4.png|right|Benzene, with the delocalization of the electrons indicated by the circle.]] In chemistry '''delocalized electrons''' are [[electron]]s in a [[molecule]] that are not associated with a single [[atom]] or to a [[covalent bond]]. Delocalized electrons are contained within an [[orbital]] that extends over several adjacent atoms. Classically, delocalized electrons can be found in [[conjugated system]]s of [[double bond]]s and in [[aromatic]] and [[mesoionic]] systems. A case of delocalized electrons occurs also in solid [[metal]]s, where the [[d orbital|d-subshell]] interferes with the above [[s orbital|s-subshell]], and contributes to the properties of a metal. It is increasingly appreciated that electrons in sigma bonding levels are also delocalized. For example, in methane, the bonding electrons are shared by all five atoms equally. Pervasive existence of delocalization is implicit in [[Molecular Orbital Theory]]. In the [[simple aromatic ring]] of [[benzene]] the '''delocalization''' of six π electrons over the C<sub>6</sub> ring is often graphically indicated by a circle. The fact that the six C-C bonds are equidistant is one indication of this delocalization. In Valence Bond Theory, delocalization in benzene is represented by [[resonance (chemistry)|resonance structures]]. Another example of a delocalized electrons can be found in a [[carboxylate]] group, wherein the negative charge is centered equally on the two oxygen atoms. Delocalized electrons are important for several reasons. One, an expected chemical reaction may not occur because the electrons delocalize to a more stable configuration, resulting in a reaction that happens at a different location. An example attempting the Fridel-Crafts alkylation of benzene with 1-chloro-2-methylpropane; the [[carbocation]] rearranges to a tert-butyl group stabilized by [[hyperconjugation]], a particular form of delocalization. Delocalized electrons also exist in the structure of [[metals]]. Metallic structure consist of aligned positive [[ions]] ([[cations]]) in a "sea" of delocalized electrons. This means that the electrons are free to move throughout the structure, and gives rise to properties such as [[electrical conductivity|conductivity]]. In diamond all four outer electrons of each carbon atom are 'localized' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane. [[Category:Chemical bonding]] [[Category:Electron]] [[ar:إلكترون غير متمركز]] [[de:Delokalisierung]] [[it:Elettrone delocalizzato]] [[nl:Gedelokaliseerd elektron]] [[fi:Delokalisaatio]] [[sv:Delokaliserad elektron]] [[zh:離域電子]]