Nitrogen
Nitrogen is a colorless, mostly unreactive gas that makes up about three-quarters of the air we breathe, yet the diatomic molecule N2 is so chemically stubborn that most living things can't use it directly. Instead, nitrogen has to be "fixed" into more reactive compounds before it becomes useful to biology or industry — a transformation at the heart of modern agriculture.
- Group · Period
- 15 · 2
- At room temp
- gas
- Melts at
- 63.15 K
- Density
- 0.0012506 g/cm³
- Discovered
- 1772
Uses
Nitrogen’s largest industrial use comes through the Haber-Bosch process, which combines atmospheric nitrogen with hydrogen to produce ammonia, the starting point for the synthetic fertilizers that support a huge share of global food production. Nitrogen gas itself is also widely used as an inert atmosphere — pumped into food packaging to keep products fresh, into shipping containers to prevent spoilage, and into industrial processes where oxygen would cause unwanted reactions like oxidation or combustion.
Liquid nitrogen serves as a cheap, effective way to reach very low temperatures, used for everything from preserving biological samples and medical tissue to rapidly freezing food and cooling sensitive equipment. Nitrogen compounds also play a central role in explosives and in the production of nylon and other industrial chemicals.
History
Nitrogen was discovered in 1772 by Scottish physician Daniel Rutherford, who was studying air left over after removing the oxygen and carbon dioxide from a sealed container. He found that this remaining gas couldn’t support combustion or animal life, and described it as “noxious air.” Other chemists of the era, including Carl Wilhelm Scheele and Henry Cavendish, independently investigated the same gas around the same time. It was later named nitrogen by French chemists, from the Greek for “nitre-forming,” since it’s a key component of saltpeter (potassium nitrate).
Fun facts
- Nitrogen makes up roughly 78% of Earth's atmosphere by volume, far more than oxygen, even though we rarely think of it as the gas we're breathing.
- The triple bond holding N2 molecules together is one of the strongest bonds in chemistry, which is exactly why nitrogen gas is so unreactive at everyday temperatures.
- Liquid nitrogen boils at about −196°C and is widely used as an inexpensive cryogenic coolant, from freezing biological samples to flash-freezing food.
Frequently asked questions
If air is mostly nitrogen, why don't we need to breathe it in to survive?
Your body inhales and exhales nitrogen gas without using it — human metabolism runs on oxygen, not N2. Nitrogen only becomes biologically useful once it's "fixed" into compounds like ammonia or nitrates, something only certain bacteria, lightning, and industrial processes can do; we get our usable nitrogen from food, not from the air itself.
Why is nitrogen such a key ingredient in fertilizer?
Nitrogen is a building block of amino acids, proteins, and chlorophyll, making it one of the nutrients plants need in the largest quantity. Soil often can't supply enough on its own, so nitrogen-based fertilizers — made possible by artificially fixing atmospheric nitrogen — are used to boost crop yields on a massive scale.
Why is nitrogen gas so unreactive?
Each N2 molecule is held together by a triple bond between its two nitrogen atoms, one of the strongest chemical bonds there is. Breaking it apart requires a lot of energy, which is why nitrogen gas sits around in the atmosphere largely unchanged rather than reacting with everything around it.
Compounds
21 notable compounds containing N
- NH3gas
Ammonia
A pyramidal molecule with a sharp, pungent odor; nitrogen's lone electron pair makes it a weak base that readily accepts a proton in water.
Used for: Fertilizer production, household cleaners, industrial refrigerant
- (NH4)6Mo7O24salt
Ammonium heptamolybdate
A white, water-soluble salt that is the most common commercial form of molybdenum, widely used as an analytical reagent and micronutrient fertilizer.
Used for: Micronutrient fertilizer and reagent for detecting phosphate in analytical chemistry
- NH4VO3salt
Ammonium metavanadate
A pale yellow-white crystalline salt that is the standard commercial starting material for manufacturing other vanadium compounds, since it decomposes cleanly to vanadium oxides on heating.
Used for: Industrial precursor for vanadium pentoxide and vanadium catalysts
- NH4ReO4industrial
Ammonium perrhenate
A white, water-soluble crystalline salt that is the main commercial form in which rhenium is sold and shipped, since it is easily purified from ore-processing streams.
Used for: Primary industrial source material for producing rhenium metal and its alloys
- Ba(NO3)2salt
Barium nitrate
A colorless, water-soluble oxidizer that burns with a vivid green flame, making it a mainstay of pyrotechnic formulations.
Used for: Green color agent and oxidizer in fireworks and flares
- BNindustrial
Boron nitride
Isoelectronic with carbon, it forms a slippery hexagonal layered structure like graphite, or an extremely hard cubic form comparable to diamond.
Used for: High-temperature lubricant, cutting tools, heat-resistant coatings
- (NH4)2Ce(NO3)6reagent
Ceric ammonium nitrate
An orange-red crystalline salt and one of chemistry's most reliable single-electron oxidants, widely known simply as CAN in organic synthesis labs.
Used for: Oxidizing reagent in organic synthesis and printed-circuit etching
- PtCl2(NH3)2pharmaceutical
Cisplatin
A square-planar platinum(II) complex bearing two ammonia and two chloride ligands arranged on the same side of the molecule, a geometry that is essential to how it binds and disrupts DNA.
Used for: Widely used chemotherapy drug for treating various cancers
- NbNindustrial
Niobium nitride
A hard ceramic compound that becomes superconducting at a relatively high temperature for a simple binary compound, making it useful in sensitive detectors.
Used for: Superconducting single-photon detectors and thin-film coatings
- HNO3acid
Nitric acid
A strong, highly corrosive oxidizing acid that slowly decomposes in light, turning older samples faintly yellow.
Used for: Fertilizer and explosives manufacturing, metal etching
- NO2gas
Nitrogen dioxide
A reddish-brown, sharp-smelling gas that exists in equilibrium with its colorless dimer, N2O4, and is a major contributor to urban smog.
Used for: Component of vehicle exhaust and smog, nitric acid production
- N2Ogas
Nitrous oxide
A linear, sweet-smelling gas nicknamed laughing gas for the mild anesthetic and euphoric effects it produces when inhaled.
Used for: Dental and medical anesthetic, aerosol propellant, engine power boost
- Pd(NO3)2salt
Palladium(II) nitrate
A water-soluble palladium salt commonly supplied as a dilute solution, used as a convenient soluble palladium source for catalyst preparation and plating.
Used for: Soluble palladium source for catalyst impregnation and plating solutions
- KNO3mineral
Potassium nitrate
Also known as saltpeter, this ionic salt forms colorless crystals and acts as a strong oxidizer when heated. It occurs naturally as efflorescent deposits in soil and caves.
Used for: Traditional ingredient in gunpowder and a common fertilizer
- Rh(NO3)3salt
Rhodium(III) nitrate
A red, water-soluble salt used as a soluble source of rhodium ion in catalyst preparation and electroplating solutions.
Used for: Rhodium source in electroplating baths and catalyst synthesis
- RbNO3salt
Rubidium nitrate
A white crystalline oxidizer salt used mainly as a laboratory source of rubidium ion and in some specialty pyrotechnic formulations.
Used for: Pyrotechnics and specialty glass and ceramics
- AgNO3salt
Silver nitrate
A water-soluble silver salt made by dissolving silver metal in nitric acid. It darkens on exposure to light or organic matter as it slowly decomposes to metallic silver, and serves as the main starting point for making most other silver compounds.
Used for: Photographic film, silver plating, and medical antiseptics
- Sr(NO3)2salt
Strontium nitrate
A colorless, water-soluble oxidizing salt best known for producing the brilliant red flares seen in fireworks and road signal flares.
Used for: Red colorant and oxidizer in fireworks and signal flares
- [Pd(NH3)4]Cl2salt
Tetraamminepalladium(II) chloride
A water-soluble coordination compound in which four ammonia molecules surround a central palladium ion, used as a convenient palladium source for plating baths.
Used for: Palladium source in electroless and electrolytic plating solutions
- Th(NO3)4salt
Thorium nitrate
A water-soluble crystalline salt once produced on an industrial scale because fabric soaked in its solution, then ignited, left behind a fragile mesh of thorium dioxide that glowed brilliantly in gas lamps.
Used for: Historic impregnating agent for gas-lantern mantles
- ZrNindustrial
Zirconium nitride
A hard, gold-colored ceramic coating material valued for its wear resistance and metallic luster, which makes it a popular substitute for gold plating.
Used for: Decorative and wear-resistant coating on tools and watch cases
Isotopes
15 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| N-14 stable | 99.6205% | Stable | — | 2,863.42 keV | 7,475.61 keV | — |
| N-15 stable | 0.3795% | Stable | — | 101.44 keV | 7,699.46 keV | — |
Show all 15 isotopes
| N-10 | — | 2.5 MeV | Proton emission (100%) | 38,800.03 keV | 3,643.67 keV | 2.50 × 106 eV |
| N-11 | — | 830 keV | Proton emission (100%) | 24,365.64 keV | 5,358.4 keV | 8.30 × 105 eV |
| N-12 | — | 11.000 ms | Electron capture / beta-plus decay (100%), Beta-plus, alpha emission (1.93%) | 17,338.07 keV | 6,170.11 keV | 4.15 × 10-14 eV |
| N-13 | — | 9.965 m | Electron capture / beta-plus decay (100%) | 5,345.48 keV | 7,238.86 keV | 7.63 × 10-19 eV |
| N-16 | — | 7.13 s | Beta-minus decay (100%), Beta-minus, alpha emission (0.0012%) | 5,683.91 keV | 7,373.8 keV | 6.40 × 10-17 eV |
| N-17 | — | 4.173 s | Beta-minus decay (100%), Beta-minus, neutron emission (95.1%), Beta-minus, alpha emission (0.0025%) | 7,870.08 keV | 7,286.23 keV | 1.09 × 10-16 eV |
| N-18 | — | 619 ms | Beta-minus decay (100%), Beta-minus, alpha emission (12.2%), Beta-minus, neutron emission (12%) | 13,113.17 keV | 7,038.56 keV | 7.37 × 10-16 eV |
| N-19 | — | 336 ms | Beta-minus decay (100%), Beta-minus, neutron emission (41.8%) | 15,856.26 keV | 6,948.55 keV | 1.36 × 10-15 eV |
| N-20 | — | 134.4 ms | Beta-minus decay (100%), Beta-minus, neutron emission (42.9%) | 21,766.5 keV | 6,709.17 keV | 3.39 × 10-15 eV |
| N-21 | — | 84 ms | Beta-minus decay (100%), Beta-minus, neutron emission (86%) | 25,231.92 keV | 6,609.02 keV | 5.43 × 10-15 eV |
| N-22 | — | 23 ms | Beta-minus decay (100%), Beta-minus, neutron emission (34%), B-2N (12%) | 31,764.81 keV | 6,378.53 keV | 1.98 × 10-14 eV |
| N-23 | — | 14.1 ms | Beta-minus decay (100%), Beta-minus, neutron emission (42%), B-2N (8%) | 36,720.43 keV | 6,236.67 keV | 3.24 × 10-14 eV |
| N-24 | — | 52 ns | Neutron emission | 46,938 keV | 5,887 keV | 8.77 × 10-9 eV |