Nitrogen (N) is the 7th element on the periodic table. Nitrogen is the fifth most abundant element in the universe, and it is also fairly common on Earth. Nitrogen is a major component of the Earth's atmosphere - about 78% of the atmosphere is nitrogen. Through a process of fractional distillation, nitrogen can be obtained from liquefied air.
Some properties of nitrogen include:
|Density (at 0oC)||2.2670 g/cm3|
|Boiling point||4098 K|
|Melting point||3823 K|
Nitrogen is used in almost all pharmacological drugs, and is found in nitrous oxide - an anesthetic. As well, liquid nitrogen is available as a relatively inexpensive cryogenic liquid used to preserve biological specimen and conduct low temperature scientific experiments.
Finally, nitrogen gas is inert (meaning that it is hard to make nitrogen have a chemical reaction) and thus it is used to create an atmosphere that prevents chemical reactions when producing semiconductors, as well as in some welding and soldering operations. Oil companies also use high pressure nitrogen to force crude oil out from the ground. Chemistry labs will also use nitrogen gas to prevent chemical reactions with the oxygen in the atmosphere.
Nitrogen oxides are poisonous, highly reactive, and generally brown in colour. They form when fuel is burned at high temperatures. Nitrogen oxides are emitted by vehicles as well as industrial sources such as power plants, industrial boilers, cement kilns, and turbines. Nitrogen oxides have problematic chemical reactions in the atmosphere with volatile organic compounds. These reactions produce smog on hot summer days. The two major nitrogen oxides that exist are NO and NO2
Nitrogen oxides are harmful to both people and the environment. To humans, exposure to nitrogen oxides can cause increased incidence of respiratory illness and infection. Longer-term exposure can lead to actual changes in the lungs. This is because nitrogen dioxide, a major nitrogen oxide, is an irritant that is a main component of smog. As well, in the atmosphere nitrogen oxides can be transformed into ozone - which has its own adverse health effects.