Nitrogen

• The most plentiful element in Earth's atmosphere
• Constituent of all living matter
• Colorless gas, liquid or solid

Nitrogen is essential to life on Earth. It is a component of all proteins, and it can be found in all living systems. Nitrogen compounds are present in organic materials, foods, fertilizers, explosives and poisons. Nitrogen is crucial to life, but in excess it can also be harmful to the environment.

Besides making up 78% of the Earth's atmosphere, nitrogen has a number of uses. Since it is an inert gas, it can be used to replace air and reduce or eliminate oxidation of materials.

The most important use is in creating ammonia, which in turn is used to make fertilizer, explosives and other materials. Finally, liquid nitrogen is used as a refrigerant for very low temperatures.