Nitrogen is a diatomic element. There are six other diatomic elements: hydrogen, oxygen, fluorine, chlorine, iodine and bromine. Diatomic molecules only form when two atoms of the same element are bonded together with no other element.
Nitrogen in its diatomic form exists in the atmosphere and comprises 78 percent of it. Nitrogen is normally an inert nonmetal, meaning it doesn't readily react, but some organisms utilize nitrogen in such a way to create amino acids and proteins. These amino acids and proteins are then used by nearly all forms of life on Earth. The human body is 3 percent nitrogen.