Science at a Distance

Nitrogen Atomic Structure


Nitrogen is a colorless, odorless gas that is the most plentiful substance in the Earth's atmosphere. It is also a critical part of some organic molecules and living matter. Nitrogen is the sixth most abundant substance in the universe, and is about 75 percent by weight of the Earth's atmosphere.

Free nitrogen is found in gases given off by volcanoes and some mineral springs. It is also found in such minerals as niter, sodium nitrate, soil, guano, ammonia, ammonium salts and sea water.

Nitrogen and Life

Animals and plants cannot use free nitrogen gas. Bacteria living in the roots of plants such as peas, take in atmospheric nitrogen, and, along with other microorganisms, convert the gas to ammonium salts and to nitrates. Plants get the nitrogen they need from the inorganic nitrogen compounds in the soil. Animals obtain the nitrogen they need from plants or from other animals.

The nitrogen content of soil where the cycle starts, is enriched and renewed by excretion and decay of animals and plants. Some of the trapped nitrogen is returned to the air as bacteria in soil decompose the nitrogen compounds and release the element back into its gaseous form.

Humans breath nitrogen in and out of their lungs all the time, without any serious side effects. The nitrogen gas dissolves slightly in the blood and circulates around the body harmlessly. Under pressure however, such as when a person dives into deep water, the amount dissolved nitrogen increases. If the decompression is slow and careful, the dissolved nitrogen comes out of the body fluids and can be removed through the lungs, but, if decompression is too rapid, the 'bends' causes great pain and even death. This sickness, is caused by bubbles of nitrogen rapidly coming out of solution in the bloodstream.


At room temperature, nitrogen gas is inert and can therefore be used as a way to exclude oxygen and moisture from chemical reactions or potentially dangerous situations. At low temperature nitrogen liquefies and in the liquid state can be used to freeze-drying food, or act as a cooling agent when transporting perishable foods.

Most of the nitrogen in this country is used (with hydrogen) to produce ammonia. Ammonia has great commercial use. It is needed in the manufacture of other nitrogen compounds, it is converted into nitric acid, nitrates, and soda ash. Ammonia also helps to launch rockets after being converted to hydrazine, a colorless, liquid, rocket fuel.

Science at a Distance
© 2000, Professor John Blamire