chemical element, symbol N and atomic number 7; most abundant element in Earth atmosphere

Nitrogen is a nonmetal chemical element. The atmosphere contains more than 78 percent of nitrogen. It has the chemical symbol N and atomic number 7. Its stable inside typically contains 14 nucleons (7 protons and 7 neutrons). It has 5 electrons in its outer shell.

Nitrogen, 00N
Allotropessee § Allotropes
Appearancecolorless gas, liquid or solid
Standard atomic weight Ar°(N)
Nitrogen in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Groupgroup 15 (pnictogens)
Periodperiod 2
Block  p-block
Electron configuration[He] 2s2 2p3
Electrons per shell2, 5
Physical properties
Phase at STPgas
Melting point63.15 K ​(−210.00 °C, ​−346.00 °F)
Boiling point77.355 K ​(−195.795 °C, ​−320.431 °F)
Density (at STP)1.2504 g/L[2] at 0 °C, 1013 mbar
when liquid (at b.p.)0.808 g/cm3
Triple point63.151 K, ​12.52 kPa
Critical point126.192 K, 3.3958 MPa
Heat of fusion(N2) 0.72 kJ/mol
Heat of vaporization(N2) 5.56 kJ/mol
Molar heat capacity(N2) 29.124 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 37 41 46 53 62 77
Atomic properties
Oxidation states−3, −2, −1, 0,[3] +1, +2, +3, +4, +5 (a strongly acidic oxide)
ElectronegativityPauling scale: 3.04
Ionization energies
  • 1st: 1402.3 kJ/mol
  • 2nd: 2856 kJ/mol
  • 3rd: 4578.1 kJ/mol
  • (more)
Covalent radius71±1 pm
Van der Waals radius155 pm
Color lines in a spectral range
Spectral lines of nitrogen
Other properties
Natural occurrenceprimordial
Crystal structurehexagonal
Hexagonal crystal structure for nitrogen
Speed of sound353 m/s (gas, at 27 °C)
Thermal conductivity25.83×10−3 W/(m⋅K)
Magnetic orderingdiamagnetic
CAS Number17778-88-0
7727-37-9 (N2)
DiscoveryDaniel Rutherford (1772)
Named byJean-Antoine Chaptal (1790)
Isotopes of nitrogen
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
13N trace 9.965 min β+ 13C
14N 99.6% stable
15N 0.4% stable
 Category: Nitrogen
| references


Cup of liquid nitrogen

Nitrogen is a colorless odorless gas at normal temperature. It is normally attached to another nitrogen atom, making a nitrogen molecule (N2). This bond is very strong. That is why many explosives contain nitrogen. The bond is broken when the explosive is made. When it explodes the bond reforms, releasing a lot of energy.

It turns into a liquid at -195.8°C and turns into a solid at -210°C. If it is compressed, it can be turned into a liquid without making it cold.

It usually does not combine with other atoms because its strong bond prevents it from reacting. Lithium is one of the few chemical elements that react with nitrogen without being heated. Magnesium can burn in nitrogen. Nitrogen also makes blue electric sparks. The blue color is caused by the atoms being excited. When they get normal again, they release light. When nitrogen is excited, it reacts with many things that it does not normally react with.

Electric spark through a tube filled with nitrogen



Many chemical compounds that are important for industrial purposes contain nitrogen ions. These include ammonia, nitric acid, nitrates and cyanides. Nitrogen comes in several oxidation states; -3, -2, -1/3, +1, +3, +4, and +5. Each of those oxidation states has its set of compounds.

Compounds in the -3 oxidation state are weak reducing agents. These include ammonia, ammonium, amide and nitrides. Amino acids and proteins contain nitrogen in this oxidation state. Hydrazine, a compound in the -2 oxidation state, is a strong reducing agent. Azides contain nitrogen in the -1/3 oxidation state. They are extremely powerful reducing agents, and most are very toxic.

Nitrous oxide contains nitrogen in the +1 oxidation state. It is used as an anesthetic. Compounds containing nitrogen in the +2 oxidation state, such as nitric oxide, are reducing agents. +3 oxidation state compounds are strong oxidizing agents and weak reducing agents. Nitrites are the most common +3 compounds. Compounds in the +4 oxidation state are strong oxidizing agents. They include nitrogen dioxide and dinitrogen tetroxide.

Compounds containing nitrogen in the +5 oxidation state are strong oxidizing agents. They are one of the more common groups of nitrogen compounds. They include nitric acid and dinitrogen pentoxide. They also include nitrates, which are used in explosives such as dynamite, nitroglycerin and trinitrotoluene.

Occurrence and preparation


Air is made up of about 78% nitrogen and about 20.95% oxygen, < 1% argon, and traces of other gasses such as carbon dioxide, and water vapor, among others. It is also in a few nitrates in the ground. Ammonium minerals are rare. Nitrogen is in proteins.

Pure liquid nitrogen can be made by cooling air. The nitrogen turns into a liquid at a different temperature than the oxygen. It can also be made by heating certain chemical compounds, such as sodium azide.

Liquid nitrogen used to freeze a balloon

Nitrogen as an element is used to prevent things from reacting with the oxygen in the air. It can be used to fill crisp bags and incandescent bulbs. It is also used to fill some tires. It can be used to make electric components like transistors. Liquid nitrogen can be used to freeze things.

Nitrogen compounds have many uses, such as anesthetics (nitrous oxide), explosives (dynamite), cleaners (ammonia), and meat (protein), and planes (fuel).

Oil companies use high pressure nitrogen to help force crude oil to the surface.

Nitrogen is also used as a way to relieve body aches. It contributes to the torn bones in your body and helps.[4]



Nitrogen was discovered by Daniel Rutherford in 1772, who called it noxious gas or fixed gas. They discovered that part of air did not burn. It was found that animals died in it. It was known as "azote". Many nitrogen compounds also contain the "azide" or "azine" letters, such as hydrazine.

In 1910, Lord Rayleigh found out that when a spark was passed through nitrogen, it made a reactive form of nitrogen. This nitrogen reacted with many metals and compounds.



  1. "Standard Atomic Weights: Nitrogen". CIAAW. 2009.
  2. "GESTIS-Stoffdatenbank". Retrieved 2017-12-29.
  3. Tetrazoles contain a pair of double-bonded nitrogen atoms with oxidation state 0 in the ring. A Synthesis of the parent 1H-tetrazole, CH2N4 (two atoms N(0)) is given in Ronald A. Henry and William G. Finnegan, "An Improved Procedure for the Deamination of 5-Aminotetrazole", _J. Am. Chem. Soc._ (1954), 76, 1, 290–291,
  4. Joseph, R. (1993). "Touch Me—Feel Me—Feed Me— Kiss Me!". The Naked Neuron. Boston, MA: Springer US. pp. 71–98. doi:10.1007/978-1-4899-6008-5_4. ISBN 978-0-306-44510-1.