hydrogen bond

A form of @A00472@ between an electronegative atom and a hydrogen atom attached to a second, relatively electronegative atom. It is best considered as an electrostatic interaction, heightened by the small size of hydrogen, which permits proximity of the interacting dipoles or charges. Both electronegative atoms are usually (but not necessarily) from the first row of the Periodic Table, i.e. N, O or F. Hydrogen bonds may be inter-molecular or @I03130@. With a few exceptions, usually involving fluorine, the associated energies are less than \(20{-}25\ \text{kJ mol}^{-1}\) (\(5{-}6\ \text{kcal mol}^{-1}\)).
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1123 [Terms] [Paper]