Nitrogen

Nitrogen is a colourless, odourless and tasteless gas that occurs in the atmosphere under normal conditions. It is an essential component of the air we breathe and makes up about 78% of the volume of the Earth's atmosphere. In the periodic table of the elements, nitrogen is listed with the symbol N and the atomic number 7. This means that every nitrogen atom has seven protons in its nucleus.

Nitrogen has remarkable physical properties. At normal pressure it has a boiling point of −196 °C, which means that at this temperature it changes from the liquid to the gaseous state. The melting point of nitrogen is −210 °C, at which it changes from the solid to the liquid state at this extremely low temperature.

These extremely low temperatures make liquid nitrogen a useful coolant in various scientific and industrial applications, such as in cryogenics and in the food industry for rapid deep-freezing.

In nature, nitrogen occurs mainly in molecular form as N₂, with two nitrogen atoms joined to one another by a very strong triple bond. This bond gives the nitrogen molecule a high level of stability. Nitrogen is also an important component of amino acids and proteins and thus plays a central role in the metabolism of all living organisms. Nitrogen is also used in agriculture as a component of fertilisers to promote plant growth.