Intermolecular hydrogen bond
This occurs when the hydrogen bonding is between H-atom of one molecule and an atom of the electronegative element of another molecule. For example (i) hydrogen bond between the molecules of hydrogen fluoride. (ii) hydrogen bond in alcohol or water molecules.
Intermolecular hydrogen bond results into association of molecules. Hence, it usually increases the melting point, boiling point, viscosity, surface tension, solubility, etc.
Intramolecular hydrogen bond
This bond is formed between the hydrogen atom and an atom of the electronegative element (F,O,N) , of the same molecule .
Intramolecular hydrogen bond results in the cyclization of the molecules and prevents their association. Consequently, the effect of this bond on the physical properties is negligible. For example, intramolecular hydrogen bonds are present in molecules such aso-nitrophenol, o-nitrobenzoic acid, etc.
