The name nitrogène was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790 when it was found that nitrogen was present in nitric acid and nitrates. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Synthetically produced ammonia and nitrates are key industrial fertilisers, and fertiliser nitrates are key pollutants in the eutrophication of water systems. This causes difficulty for both organisms and industry in converting N 2 into useful compounds, but at the same time it means that burning, exploding, or decomposing nitrogen compounds to form nitrogen gas releases large amounts of often useful energy. The extremely strong triple bond in elemental nitrogen (N≡N), the second strongest bond in any diatomic molecule after carbon monoxide (CO), dominates nitrogen chemistry. Many industrially important compounds, such as ammonia, nitric acid, organic nitrates ( propellants and explosives), and cyanides, contain nitrogen. The nitrogen cycle describes the movement of the element from the air, into the biosphere and organic compounds, then back into the atmosphere. The human body contains about 3% nitrogen by mass, the fourth most abundant element in the body after oxygen, carbon, and hydrogen. Nitrogen occurs in all organisms, primarily in amino acids (and thus proteins), in the nucleic acids ( DNA and RNA) and in the energy transfer molecule adenosine triphosphate. N 2 forms about 78% of Earth's atmosphere, making it the most abundant uncombined element. At standard temperature and pressure, two atoms of the element bind to form N 2, a colorless and odorless diatomic gas. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. Nitrogen is the chemical element with the symbol N and atomic number 7.
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