Here's why:

* Nitrogen makes up about 78% of the Earth's atmosphere. This means that most of the air we breathe is nitrogen gas (N2).

* It's a diatomic molecule, meaning two nitrogen atoms bond together to form a stable molecule.

* Nitrogen gas is relatively unreactive at normal temperatures and pressures.

While other elements can exist as gases under certain conditions, nitrogen is the most common element found in a gaseous state on Earth.