Nitrogen

Nitrogen is the non-metallic chemical element of atomic number 7, with a symbol N, atomic weight 14.0067, specific gravity 0.96737 (compared to air), melting point -345.74°F (-209.86°C), boiling point -320.44°F (-195.8°C).

Nitrogen is a non-metallic element located in group 15 of the periodic table. It has two stable isotopes: nitrogen-14, with an abundance of 99.634%, and nitrogen-15, with an abundance of 0.366%. At least five radioactive isotopes of the element have been prepared, with atomic weights of 12, 13, 16, 17, and 18.

Credit for the discovery of nitrogen is usually given to the Scottish physician Daniel Rutherford in 1772, although Henry Cavendish, Joseph Priestly, and Carl Scheele could also claim to have discovered the element at about the same time. Nitrogen was first identified as the product left behind when a substance was burned in a closed sample of air (which, of course, removed the oxygen component of air).