Physical Properties

Every element in Group 15 is polyatomic in its elemental form, but dinitrogen is the odd one out — it exists as the diatomic gas $N_2$, whereas all the other members of the group are solids at room temperature. Metallic character increases steadily down the group, mirroring the fall in ionisation enthalpy and the growth in atomic size: nitrogen and phosphorus are non-metals, arsenic and antimony are metalloids, and bismuth is a true metal. …