covalent bond

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the linkage between atoms or radicals of a chemical compound, or the symbol representing this linkage and indicating the number and attachment of the valencies of an atom in constitutional formulas, represented by a pair of dots or a line between atoms, e.g., H—O—H, H—C≡C—H or H:O:H, H:C:::C:H.
coordinate covalent bond a covalent bond in which one of the bonded atoms furnishes both of the shared electrons.
covalent bond a chemical bond between two atoms or radicals formed by the sharing of a pair (single bond), two pairs (double bond), or three pairs of electrons (triple bond).
disulfide bond a strong covalent bond, —S—S—, important in linking polypeptide chains in proteins, the linkage arising as a result of the oxidation of the sulfhydryl (SH) groups of two molecules of cysteine.
high-energy phosphate bond an energy-rich phosphate linkage present in adenosine triphosphate (ATP), phosphocreatine, and certain other biological molecules. On hydrolysis at pH 7 it yields about 8000 calories per mole, in contrast to the 3000 calories yielded by phosphate esters. The bond stores energy that is used to drive biochemical processes, such as the synthesis of macromolecules, contraction of muscles, and the production of the electrical potentials for nerve conduction.
high-energy sulfur bond an energy-rich sulfur linkage, the most important of which occurs in the acetyl-CoA molecule, the main source of energy in fatty acid biosynthesis.
hydrogen bond a weak, primarily electrostatic, bond between a hydrogen atom bound to a highly electronegative element (such as oxygen or nitrogen) in a given molecule, or part of a molecule, and a second highly electronegative atom in another molecule or in a different part of the same molecule.
ionic bond a chemical bond in which electrons are transferred from one atom to another so that one bears a positive and the other a negative charge, the attraction between these opposite charges forming the bond.
peptide bond the —CO—NH— linkage formed between the carboxyl group of one amino acid and the amino group of another; it is an amide linkage joining amino acids to form peptides.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
References in periodicals archive ?
However, the compound has more signals compared to GB-5, such as a set of double-bond signals, a hydroxymethyl signal ([[delta].sub.c] 62.8), and a set of glucose signal ([[delta].sub.c] 104.9, 78.8, 78.5, 76.1, and 62.6).
Double-bond conversion ranged from 32.75% to 78.50% for BisGMA/BisEMA blends, and from 32.75% to 76.22% for BisGMA/TEGD MA blends.
Moreover, the double-bond edges are suitable for the dye to align on Ti[O.sub.2] electrodes that exhibit high photovoltaic performance by the short dye-uptake time (for 1h).
(1994) The first genuine silicon-sulfur double-bond compound--synthesis and crystal structure of a kinetically stabilized silanethione.
The complete process model for the synthesis of unsaturated polyester process should be composed of (1) a detailed kinetic model consisting of changing order rate equations for polyesterification, isomerization, and double-bond saturation reactions, (2) a thermodynamic model to obtain components compositions at interphase of vapor and liquid, and (3) a mass transfer model to predict mass transfer from liquid-to-vapor phase.
The water in the system possibly brings silane condensation to form a compound with two or more double-bond at a low temperature area in the extruder, and then the compound reacts with the PP macroradical.
Its two pairs of double-bonded carbons are separated by a pair of single-bonded ones.
The analysis exhibits a shift of double-bonds after peroxide treatment.
The second reaction induces two molecules to exchange chain portions from either side of the double-bonded carbons.
Developed by LLNL, Sandia National Laboratories, Albuquerque, NM, and the National Renewable Energy Laboratory, Golden, CO, the detoxification system destroys TCE, a double-bonded carbon compound, and possibly other solvents, including tetrachloroethylene, perchloroethylene (PCE), and dichloroethylene.
They may have double-bonded carbons that cause the chains to bend.