Nitrogen and Phosphorus

Nitrogen in its elemental form is a non-metallic gas that makes up 78 percent of Earth's atmosphere.

Nitrogen compounds, and especially their oxidized derivatives, are important in biological systems and as explosives.

Phosphorus is found in its elemental form as different allotropes, none of which are stable in the presence of oxygen.

Phosphorus compounds consist mostly of compounds containing strong phosphorus-oxygen bonds. They are important in fertilizers and biology.