<P> The hydrogen bond is an attractive interaction between a hydrogen atom from a molecule or a molecular fragment X--H in which X is more electronegative than H, and an atom or a group of atoms in the same or a different molecule, in which there is evidence of bond formation . </P> <P> An accompanying detailed technical report provides the rationale behind the new definition . </P> <P> A hydrogen atom attached to a relatively electronegative atom will play the role of the hydrogen bond donor . This electronegative atom is usually fluorine, oxygen, or nitrogen . A hydrogen attached to carbon can also participate in hydrogen bonding when the carbon atom is bound to electronegative atoms, as is the case in chloroform, CHCl . An example of a hydrogen bond donor is the hydrogen from the hydroxyl group of ethanol, which is bonded to an oxygen . </P> <P> In a hydrogen bond, the electronegative atom not covalently attached to the hydrogen is named proton acceptor, whereas the one covalently bound to the hydrogen is named the proton donor . </P>

How does electronegativity play a role in hydrogen bonding
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