Abundance in earth
Nitrogen composes about four-fifths (78.03 per cent) by volume
of the atmosphere. Nitrogen is inert and serves as a diluter for oxygen in
burning and respiration processes. It is an important element in plant nutrition;
certain bacteria in the soil convert atmospheric nitrogen into a form, such as
nitrate, that can be absorbed by plants, a process called nitrogen fixation.
Nitrogen in the form of protein is an important constituent of animal tissue.
The element occurs in the combined state in minerals, of which saltpetre (KNO3)
and Chile saltpetre (NaNO3) are commercially important products.
Electron diagram of
Nitrogen
N
Electric
Discharge in Nitrogen
This discharge tube contains nitrogen gas at low pressure.
When the tube is connected to a high voltage source, electrons flow from the
cathode at one end of the tube to the anode at the other end. Some of the
electrons collide with the nitrogen in the tube, exciting the nitrogen atoms.
These excited atoms quickly shed their excess energy by emitting light, whose
combined effect results in the purplish glow visible above.