Nitrogen

Nitrogen, ₇N
General properties
Appearance	colorless gas, liquid or solid
Standard atomic weight (Ar, standard)	[14.00643, 14.00728]
Nitrogen in the periodic table
	carbon ← nitrogen → oxygen
Atomic number (Z)	7
Group	group 15 (pnictogens)
Period	period 2
Block	p-block
Element category	reactive nonmetal
Electron configuration	[He] 2s2 2p3
Electrons per shell	2, 5
Physical properties
Phase at STP	N: Gas
Melting point	63.15 K (−210.00 °C, −346.00 °F)
Boiling point	77.355 K (−195.795 °C, −320.431 °F)
Density (at STP)	1.2504 g/L at 0 °C, 1013 mbar
when liquid (at b.p.)	0.808 g/cm3
Triple point	63.151 K, 12.52 kPa
Critical point	126.192 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)
Atomic properties
Oxidation states	−3, −2, −1, +1, +2, +3, +4, +5 (a strongly acidic oxide)
Electronegativity	Pauling scale: 3.04
Ionization energies	1st: 1402.3 kJ/mol ; 2nd: 2856 kJ/mol ; 3rd: 4578.1 kJ/mol ; (more) ;
Covalent radius	71±1 pm
Van der Waals radius	155 pm
	Spectral lines of nitrogen
Other properties
Natural occurrence	N: Primordial
Crystal structure	hexagonal
Speed of sound	353 m/s (gas, at 27 °C)
Thermal conductivity	25.83×10−3 W/(m·K)
Magnetic ordering	diamagnetic
CAS Number	17778-88-0 ; 7727-37-9 (N2)
History
Discovery	Daniel Rutherford (1772)
Named by	Jean-Antoine Chaptal (1790)
Main isotopes of nitrogen
	view; talk; edit; \| references

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.

Properties

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

Compounds

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.

Uses

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.^[3]

In at least one country (as of the 2020s), Nitrogen gas is used for execution of a person, when the justice system orders that person to be killed.^[4]

History

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.

NitrogenCompounds Media

Daniel Rutherford, discoverer of nitrogen
The shapes of the five orbitals occupied in nitrogen. The two colours show the phase or sign of the wave function in each region. From left to right: 1s, 2s (cutaway to show internal structure), 2px, 2py, 2pz.
Molecular orbital diagram of dinitrogen molecule, N2. There are five bonding orbitals and two antibonding orbitals (marked with an asterisk; orbitals involving the inner 1s electrons not shown), giving a total bond order of three.
Solid nitrogen on the plains of Sputnik Planitia (on the bottom-right side of the image) on Pluto next to water ice mountains (on the up-left side of the image)
Structure of [Ru(NH3)5(N2)]2+ (pentaamine(dinitrogen)ruthenium(II)), the first dinitrogen complex to be discovered
Mesomeric structures of borazine, (–BH–NH–)3
Standard reduction potentials for nitrogen-containing species. Top diagram shows potentials at pH 0; bottom diagram shows potentials at pH 14.
Nitrogen trichloride
Nitrogen dioxide at −196 °C, 0 °C, 23 °C, 35 °C, and 50 °C. NO₂ converts to colourless dinitrogen tetroxide (N₂O₄) at low temperatures, and reverts to NO₂ at higher temperatures.