covalent bond

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Related to covalent bond: nonpolar covalent bond, Noncovalent bond


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 ?
Caption: FIGURE 5: The condensation of Schiff-base coupling reaction occurred between TAPP and TPA, sequential (a-c) images acquired in the same location, and corresponding structural models (a'-c') clearly demonstrate covalent bond formation/cleavage dynamics.
For the irreversible binding step, the formation of covalent bonds between [Cys.sub.273] and [Mdha.sup.7] should overcome the hydrogen bonds between [Cys.sub.273] and [Asn.sub.278].
bonded to two oxygen atoms of hydroxyl group by covalent and two oxygen atoms of the acetyl group by coordinate covalent bonds to form distorted square planner geometry.
are considered to be 1.68794 A2,0.453456 A4, and 0.22682 A4, respectively, and the covalent bond distance of the carbon where [M], [K], {q}, and {[??]} indicate the global mass matrix, global stiffness matrix, nodal displacement vector, and nodal acceleration vector, respectively.
The overlap population decreases, covalent bond is weakened, and bond length between Ga and N increases for N vacancy defect surface as shown in Table 2 caused mainly by the decrease of charges of N and Ga atoms (see Table 1) compared with that of intact surface.
These basecoats are designed such that they form covalent bonds with the hyaluronan topcoat, ensuring excellent intercoat adhesion.
Finite element approach, which is used in this paper, is based on the substitution of covalent bonds between atoms with beam elements, and is described in detail in Section 3.1.
To illustrate covalent bond formation based on the magnetic interaction, we examine the covalent bonds in hydrogen gas (like atoms) and hydrogen chloride (unlike atoms).
The two bonds between an oxygen and each of the hydrogen atoms in a water molecule are covalent bonds. However, as stated earlier, the master of the covalent bond is carbon.
reported that an maleic anhydride (MAH)-based third component, a so called sizing agent, acted as a bridging role in aminosilane-treated GF/nylon-6,6 composite and affected the strong interfacial interaction between the GF and nylon-6,6 via covalent bond formation [4].
Scheme-1 shows the mechanism for the formation of covalent bond between 2ME and NTCOOH (COOH mechanism) where k1 is rate constant and K1 and K 1 are equilibrium constants.