covalent bond

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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.
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 It might be outdated or ideologically biased.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.


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

covalent bond

[kō′vā·lənt ′bänd]
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.
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Although these IR spectra themselves do not provide direct evidence for any covalent bonding between the PNIPA hydrogel and modified silica, the results indicating the presence of ester carbonyl groups in the absence of any double bonds in the PNIPA/modified silica hydrogel suggested that the double bonds introduced on the modified silica were copolymerized with NIPA and that the modified silica was bound with PNIPA hydrogel via covalent bonding.
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