Nitrogen
Element 7 · Nonmetal
Nitrogen gas dominates every breath you take, and almost none of it reacts: two nitrogen atoms share a triple bond so strong that N2 ignores nearly everything at room temperature. Life still cannot do without it. Specialized bacteria and the Haber-Bosch process crack that triple bond to make ammonia, which becomes the fertilizer feeding half of humanity. Nitrogen atoms sit at the core of amino acids, proteins, DNA, and the energy molecule ATP. Liquid nitrogen, boiling at -195.79 °C, flash-freezes food and preserves biological samples.
Key facts
| Atomic number | 7 |
|---|---|
| Atomic weight | 14.007 |
| Category | Nonmetal |
| Group / Period | 15 / 2 |
| Block | p |
| Electron configuration | 1s2 2s2 2p3 |
| Common oxidation states | +5, +4, +3, +2, +1, -3 |
| State at STP | Gas |
| Electronegativity | 3.04 |
| Atomic radius | 56 pm |
| Density | 0.00125 g/cm³ |
| Melting point | -210.1 °C |
| Boiling point | -195.79 °C |
Occurrence
Nitrogen gas is 78 percent of Earth's atmosphere by volume. Fixed nitrogen reaches soil as nitrates through lightning, bacteria, and fertilizers, then cycles through plants and animals back to the air.
Applications
Ammonia and nitrogen fertilizers
Liquid nitrogen coolant
Inert atmospheres for food packaging
Nitric acid production
Electronics manufacturing
Common compounds
- Ammonia (NH3)
- Nitric acid (HNO3)
- Urea ((NH2)2CO)
- Nitrogen dioxide (NO2)
Every lightning bolt fixes nitrogen from the air, raining down natural fertilizer with each thunderstorm.
Data source: IUPAC standard atomic weights 2021