In solids, the valence band is the highest range of electron energies where electrons are normally present at absolute zero. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Absolute zero is the point at which molecules do not move (relative to the rest of the body more than they are required to by a quantum mechanical effect called Zero-point In semiconductors and insulators, there is a band gap above the valence band, followed by a conduction band above that. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that An insulator, also called a Dielectric, is a material that resists the flow of Electric current. In Solid state physics and related applied fields a band gap, also called an energy gap or bandgap, is an energy range in a solid where no electron states In the Physics field of Semiconductors and insulators the conduction band is the range of Electron Energy, higher than that of the In metals, the conduction band has no energy gap separating it from the valence band (basically, this is correct only for semimetals. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across A semimetal is a material with a small overlap in the energy of the conduction band and Valence bands However the bottom of the conduction band is All solids have forbidden energy levels between the energy bands). The rest of this article refers to the valence band in semiconductors and insulators.

Semiconductors and insulators owe their low conductivity to the properties of the valence band in those materials. Electrical conductivity or specific conductivity is a measure of a material's ability to conduct an Electric current. It just so happens that the number of electrons is precisely equal to the number of states available up to the top of the valence band. There are no available states in the band gap. This means that when an electric field is applied, the electrons cannot increase their energy (i. In Physics, the space surrounding an Electric charge or in the presence of a time-varying Magnetic field has a property called an electric field (that can e. , accelerate) because there are no states available to the electrons where they would be moving faster than they are already going.

There is some conductivity in insulators, however. This is due to thermal excitation—some of the electrons get enough energy to jump the band gap in one go. Once they are in the conduction band, they can conduct electricity, as can the hole they left behind in the valence band. An electron hole is the conceptual and mathematical Opposite of an Electron, useful in the study of Physics and Chemistry. The hole is an empty state that allows electrons in the valence band some degree of freedom.

It is a common misconception to refer to electrons in insulators as "bound"—as if they were somehow attached to the nucleus and could not move. Electrons in insulators are free to move. They are also delocalized, having no well-defined position within the sample.

See also

• Semiconductor for a full explanation of the band structure of materials. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that
• Electrical conduction for more information about conduction in solids, and another description of band structure. Electrical conduction is the movement of electrically charged particles through a Transmission medium ( Electrical conductor)
• Conduction band
• Band Theory
• Fermi sea

References

• Chembio
• Hyperphysics

In the Physics field of Semiconductors and insulators the conduction band is the range of Electron Energy, higher than that of the In Solid-state physics, the electronic band structure (or simply band structure) of a Solid describes ranges of Energy that an Electron Fermi liquid is a generic term for a quantum mechanical Liquid of Fermions that arises under certain physical conditions when the Temperature

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic