When hydrogen (H) is covalently bonded to a highly electronegative atoms(X= O, N, Cl), the shared electron pair is pulled so close to X that a strong dipole results.
Xδ- :─H δ+
When hydrogen forms a bridge between two electronegative atoms of adjoining molecules, it is said to form a “hydrogen bond”. Thus the familiar examples of water molecules which are polar in character have hydrogen bonds are represented by dotted lines:
:Xδ-─H δ+ + :Xδ-─H δ+ → :Xδ-─H δ+…….:Xδ-─H δ+
Hydrogen bonds in water:
