covalent bond

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Related to Covalent bonds: Covalent Compounds, Polar covalent bonds

covalent bond

(kō'vā`lənt): see chemical bondchemical bond,
mechanism whereby atoms combine to form molecules. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the formation of an aggregate with sufficient stability to be regarded as an
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The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Covalent Bond

 

a chemical bond between two atoms that is formed by a shared electron pair (one electron from each atom). Covalent bonds exist both in molecules (in all states of aggregation) and between the atoms that form crystal lattices. They may unite like atoms (in H2 and C12 molecules and diamond crystals) or unlike atoms (in water molecules and crystals of carborundum, SiC).

Almost all the main bonds in the molecules of organic compounds are covalent (C—C, C—H, C—N, and so on). Covalent bonds are very strong, which explains the low chemical activity of paraffin hydrocarbons. Many inorganic compounds whose crystals have an atomic lattice (that is, are formed by a covalent bond) are refractory and characterized by great hardness and wear resistance; among them are certain carbides, suicides, borides, and nitrides (particularly borazone, BN), which are widely used in modern technology.

V. A. KIREEV

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

covalent bond

[kō′vā·lənt ′bänd]
(chemistry)
A bond in which each atom of a bound pair contributes one electron to form a pair of electrons. Also known as electron pair bond.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The additional specificity of the second dimension (photo cross-linking) derives from the requirement that the target amino acid must be positioned appropriately both in distance and orientation to yield the covalent bond (13, 19).
The band at 1635 [cm.sup.-1] almost completely disappears, suggesting that the M-POSS structures are chemically incorporated into the hybrid materials and form a cross-linking network structure in covalent bonds. The band at 1116 [cm.sup.-1] is assigned as Si-O-Si implied the hybrid materials with cage structure of POSS.
Over the course of the reaction, hydroxyl groups of the coupling agent condense with end of hydroxyl groups from an inorganic substrate as a result of dehydration, then produce covalent bonds. In the meantime, the organo-functional group of the silane molecule at another end reacts with the organic material to produce a covalent bond.
3, there was no direct evidence for the formation of covalent bonds between PNIPA and the modified silica.
The covalent bonds that give way, the team suggests, are carbon-silicon bonds for the glass surface and sulfur-gold bonds for the gold surface.
Solvent extraction results confirm that there are no covalent bonds between PMMA and the inorganic phases.
A new study of ice now shows experimentally that the frail hydrogen bond between water molecules taps into a molecule's internal covalent bonds, formed when atoms share electrons.
FTIR study shows that covalent bonds are formed between ABS chains and silica nanoparticles.
In this transformation, the strong, covalent bonds that normally link two hydrogen atoms to a single oxygen atom in a water molecule would become indistinguishable from the hydrogen bonds that link neighboring molecules.
For the application as an adhesion promoter, the pp-GMA layer should be tethered to the HDPE substrate permanently via covalent bonds while at the same time retaining the epoxide functional groups.
Snyderwine and her National Cancer Institute colleagues in Bethesda, Md., reported at AACR that the liver-activated forms of the heterocyclic amines IQ and PhIP form abducts--or covalent bonds to DNA--in human breast cells grown in the lab.
The surface of the LDPE film after removing the ONy layer consisted of untreated LDPE, PA6 with TFE, and only a trace of [N/C] value, These results suggest that both the hydrogen bonds and the covalent bonds were formed at the interface of the PA6 and LDPE layer during NACELP.