A chemical element with the atomic number 7. Nitrogen is relatively abundant in Universe and is a component of all living organisms. On Earth, it takes the form of a colourless, tasteless, odourless gas that makes up 78 percent of the Earth’s atmosphere. It is also extracted from the atmosphere industrially and used to produce a range of compounds such as fertilisers. A nitrogen atmosphere is used to prevent oxidation, for example in food packaging. Liquid nitrogen at temperatures below −195 °C is used as a refrigerant in various technological processes or in medicine for the preservation of biological samples.