Liquid ammonia (NH3) and water (H2O) both show hydrogen bonding, describe what a hydrogen bond is and what it is conferred by

A hydrogen bond forms between the positive dipole of one molecule and the negative dipole of another molecule. They can be represented on a diagram with a dashed line perpendicular (at 90˚) to the bond angle between the two dipoles. This is due to a significant difference in electronegativity (measured on the Pauling scale) of the atoms in the molecule (e.g. the highly electronegative nitrogen in ammonia and the three other hydrogen atoms). The electron cloud is pulled towards the nitrogen atom in the bond.