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Nitrogen (N), element 7
Nitrogen (N) is the chemical element with atomic number 7: a nonmetal in group 15, period 2. At 25 °C it is a gas, with an atomic mass of 14.01 u.
Physical and chemical data
| Atomic number | 7 |
|---|---|
| Symbol | N |
| Atomic mass | 14.01 u |
| Density | 0.001251 g/cm³ |
| Melting point | -210 °C (63.15 K) |
| Boiling point | -195.79 °C (77.36 K) |
| Electronegativity (Pauling) | 3.04 |
| Electron configuration | [He] 2s2 2p3 |
| Atomic radius (van der Waals) | 155 pm |
| Oxidation states | +5, +4, +3, +2, +1, -1, -2, -3 |
| Physical state at 25 °C | gas |
| Family | nonmetal |
| Group and period | 15 / 2 |
| Discoverer and year | Daniel Rutherford (1772) |
The discovery record belongs to Daniel Rutherford, in 1772.
Neighbours on the table
Horizontally, one proton less lands on Carbon (Z=6); one more lands on Oxygen (Z=8). Vertically, group 15 gathers relatives with similar behaviour: Phosphorus, Arsenic, Antimony, Bismuth.
The story behind the name
Daniel Rutherford described it in 1772 as noxious air, what remained after a candle and a mouse had used up the breathable part of a flask. The official name comes from nitre (saltpetre) plus genes, saltpetre maker, but Lavoisier preferred azote, Greek for lifeless, and that name stuck in part of the world: French still calls it azote today. Lifeless is unfair: every breath you take is 78% nitrogen, and it sits in every protein of your body.
Physical and chemical data: PubChem Periodic Table (NCBI, compiling NIST and IUPAC), public domain, snapshot of 2026-07-10. Temperatures converted from kelvin; historical notes cross checked against classic chemistry references.
Last updated: · Methodology and sources