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How does hydrogen bonding affect ammonia molecules?

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Difference in molecular structure between ammonia/amines and quaternary ammonium ions — ammonia Ammonia and amines have a slightly flattened trigonal pyramidal shape with a lone pair of electrons above the nitrogen. In quaternary ammonium ions, this area is occupied by a fourth substituent.

Ammonia (NH₃) is a polar molecule with a trigonal pyramidal shape, featuring a nitrogen atom bonded to three hydrogen atoms and an unshared pair of electrons. Because of these structural characteristics, ammonia molecules are highly associated through strong intermolecular hydrogen bonding.12

This extensive hydrogen bonding significantly affects the physical properties of ammonia, most notably its boiling point. Ammonia exhibits a much higher boiling point than its heavier chemical analogues, such as phosphine (PH₃), because additional thermal energy is required to break these hydrogen bonds to permit vaporization.3

Furthermore, while ammonia's dielectric constant is lower than that of water, the presence of these interactions allows it to function as a moderately good ionizing solvent for various chemical substances.1