Interaction involving a hydrogen atom located between a pair of other atoms having a high affinity for electrons; such a bond is weaker than an ionic bond or covalent bond but stronger than van der Waals forces .
Hydrogen bonds can exist between atoms in different molecule s or in parts of the same molecule. One atom of the pair (the donor), generally a fluorine , nitrogen , or oxygen atom, is covalently bonded to a hydrogen atom ( 2015; FH, 2015; NH, or 2015; OH), whose electrons it shares unequally; its high electron affinity causes the hydrogen to take on a slight positive charge. The other atom of the pair, also typically F, N, or O, has an unshared electron pair, which gives it a slight negative charge. Mainly through electrostatic attraction, the donor atom effectively shares its hydrogen with the acceptor atom, forming a bond. Because of its extensive hydrogen bonding, water (H 2 O) is liquid over a far greater range of temperatures that would be expected for a molecule of its size. Water is also a good solvent for ionic compounds and many others because it readily forms hydrogen bonds with the solute. Hydrogen bonding between amino acid s in a linear protein molecule determines the way it folds up into its functional configuration . Hydrogen bonds between nitrogenous bases in nucleotide s on the two strands of DNA ( guanine pairs with cytosine , adenine with thymine ) give rise to the double-helix structure that is crucial to the transmission of genetic information.