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In coordination chemistry, a coordinate covalent bond, [1] also known as a dative bond, [2] dipolar bond, [1] or coordinate bond [3] is a kind of two-center, two-electron covalent bond in which the two electrons derive from the same atom. The bonding of metal ions to ligands involves this kind of interaction. [4]
The term chelate derives from the Greek word for “claw,” and is applied to name ligands, which attach to a metal ion with two or more donor atoms through dative bonds. The fluorescence is most intense when the metal ion has the oxidation state of 3+. Not all lanthanide metals can be used and the most common are: Sm(III), Eu(III), Tb(III ...
Instead of simply assigning a charge (oxidation state) to an atom in the molecule, the covalent bond classification method analyzes the nature of the ligands surrounding the atom of interest. [2] According to this method, the interactions that allow for coordination of the ligand can be classified according to whether it donates two, one, or ...
Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.
The change from an A*-G grading system to a 9-1 grading system by English GCSE qualifications has led to a 9-1 grade International General Certificate of Secondary Education being made available. [13] Before, this qualification was graded on an 8-point scale from A* to G with a 9th grade “U” signifying “Ungraded”.
The strong bonding of metals in liquid form demonstrates that the energy of a metallic bond is not highly dependent on the direction of the bond; this lack of bond directionality is a direct consequence of electron delocalization, and is best understood in contrast to the directional bonding of covalent bonds.
In DNA-ligand binding studies, the ligand can be a small molecule, ion, [1] or protein [2] which binds to the DNA double helix. The relationship between ligand and binding partner is a function of charge, hydrophobicity, and molecular structure. Binding occurs by intermolecular forces, such as ionic bonds, hydrogen bonds and Van der Waals forces.
The first description of cooperative binding to a multi-site protein was developed by A.V. Hill. [4] Drawing on observations of oxygen binding to hemoglobin and the idea that cooperativity arose from the aggregation of hemoglobin molecules, each one binding one oxygen molecule, Hill suggested a phenomenological equation that has since been named after him: