Hydrogen Bond

Type of attractive intermolecular force that exists between two partial electric charges of opposite polarity. Although stronger than most other intermolecular forces, the typical hydrogen bond is much weaker than both the ionic bond and the covalent bond. When H bonds with a strongly electronegative element (such as O) the electronegative element attracts the electron cloud from around the hydrogen nucleus and, by decentralizing the cloud, leaves the atom with a positive partial charge. The resulting charge, though only partial, nevertheless represents a large positive charge density that is attracted to sites of negative charge. The hydrogen bond is not a simple attraction between point charges, but possesses some degree of orientation preference. Consequently, it has some of the characteristics of a covalent bond. This covalency tends to be more extreme when acceptors bind H from more electronegative donors.

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Hydrogen bonds form the crystal structure of ice, bond layers in some phyllosilicates, connect the two strands of deoxyribonucleic acid (DNA) by joining attached amino acids (below), and play a major role in the folding of proteins.

Some or all content above used with permission from J. H. Wittke.