Nitrogen was discovered by Daniel Rutherford in 1772. The word nitrogen originated from the Latin word nitrum and the Greek word nitro, meaning native soda.
Nitrogen (N2) is a colorless, odorless and tasteless gas that makes up 78.09% (by volume) of the air we breathe. Naturally occurring nitrogen contains two isotopes, 14N and 15N, with a relative abundance of 99.62% and 0.38%, respectively.
Atomic number : 7
Atomic mass : 14.0067 g.mol -1
Vanderwaals radius : 0.092 nm
Ionic radius : 0.171 nm (-3) ; 0.011 (+5) ; 0.016 (+3)
Isotopes : 4
Electronic shell : [ He ] 2s22p3
Nitrogen Physical Properties
- It is a relatively inert gas.
- It is colorless, odorless and tasteless.
- Liquid nitrogen is also colorless and odorless, and is similar in
appearance to water.
- There are two allotropic forms of solid nitrogen, a and b, with a
transition between the two forms at -237° C.
- Density : 1.25*10-3 g.cm-3 at 20°C
- Melting point : -210 °C
- Boiling point : -195.8 °C
- Nitrogen form compounds through biological activity, at high
temperature, or at moderate temperature with the aid of catalysts.
- It forms nitric oxide and nitrogen dioxide with oxygen, ammonia
with hydrogen, and nitrogen sulfide with sulfur.
- At high temperatures it will combine with certain active metals,
such as lithium, magnesium and titanium to form nitrides.
- It is non flammable and will not support combustion.
- Energy of first ionisation : 1402 kJ.mol -1
- Energy of second ionisation : 2856 kJ.mol -1
- Energy of third ionisation : 4577 kJ.mol -1
- Electronegativity according to Pauling : 3.0