Nitrogen in its elemental form is a non-metallic gas that makes up 78
percent of Earth's atmosphere.
LEARNING OBJECTIVE [ edit ]
Discuss the properties of nitrogen.
KEY POINTS [ edit ]
Nitrogen is a chemical element with symbol N and atomic number 7. Elemental nitrogen is a
colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting
78.09 percent of Earth's atmosphere by volume.
Nitrogen gas is an industrial gas produced by the fractional distillation of liquid air or by
mechanical means using gaseous air. Commercial nitrogen is often a byproduct of air-processing
for industrial concentration of oxygen.
Nitrogen gas has a variety of applications, including serving as an inert replacement for air
where oxidation is undesirable. Liquid nitrogen is also used to cryogenically freeze objects.
TERMS [ edit ]
elemental
Of, relating to, or being an element (as opposed to a compound).
amino acid
Generally, molecules that contain both an amino and a carboxylic acid functional group. The
monomers from which polypeptide chains, or proteins, are built are amino acids.
nitrogen
A chemical element (symbol N) with an atomic number of 7 and atomic weight of 14.0067 amu.
Give us feedback on this content: FULL TEXT [edit ]
The elementnitrogen was discovered as a separable component of air by Scottish physician
Daniel Rutherford in 1772.
Nitrogen compounds were well known
during the Middle Ages. Alchemists knew
nitric acid as aqua fortis (strong water).
The mixture of nitric and hydrochloric
acids was known as aqua regia (royal
water), celebrated for its ability to dissolve
gold (the king of metals). The earliest
military, industrial, and agricultural
applications of nitrogen compounds used
saltpetre (sodium nitrate or potassium
Register for FREE to stop seeing ads
nitrate), most notably in gunpowder and later as fertilizer.
Nitrogen is a chemical element with symbol N and atomic number 7. Elemental nitrogen is a
colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions,
constituting 78.09 percent of Earth's atmosphere by volume. Nitrogen is a common element
in the universe, estimated at about seventh in total abundance in our galaxy and the
solarsystem. Its occurrence there is thought to be entirely due to synthesis by fusion of
carbon and hydrogen in supernovas. Due to the volatility of elemental nitrogen and its
compounds with hydrogen and oxygen, nitrogen is far less common on the rocky planets of
the inner solar system and is a relatively rare element on Earth. However, as on Earth,
nitrogen and its compounds occur commonly as gases in the atmospheres of planets and
moons.
Nitrogen in Living Systems
Nitrogen occurs in all living organisms, primarily in amino acidswhich make up proteins, and
nucleic acids (DNA and RNA). The human body is about three percent nitrogen by weight,
the fourth-most abundant element after oxygen, carbon, and hydrogen. Nitrogen resides in
the chemical structure of almost all neurotransmitters and is a defining component of
alkaloids, biological molecules produced as secondary metabolites by many organisms.
The nitrogen cycle describes the movement of the element from the air into the biosphere
and organic compounds and back into the atmosphere. Synthetically produced nitrates are
key ingredients of industrial fertilizers and key pollutants causing the eutrophication of water
systems.
The Nitrogen Cycle
The figure summarizes the major processes through which nitrogen is converted between its various
forms on the surface of the earth.
Industrial Production of Nitrogen
Nitrogen gas is an industrial gas produced by the fractional distillation of liquid air or by
mechanical means using gaseous air (i.e., pressurized reverse osmosis membrane or pressure
swing adsorption). Commercial nitrogen is often a byproduct of air-processing for
industrial concentration of oxygen forsteelmaking and other purposes. When supplied
compressed in cylinders, it is often called OFN (oxygen-free nitrogen).
In a chemical laboratory it is prepared by treating an aqueoussolution of ammonium chloride
with sodium nitrite, or through the decomposition of sodium azide:
N H 4 Cl(aq) + N aN O 2 (aq)
→
N 2 (g) + N aCl(aq) + 2H 2 O(l) 2N aN 3
→
2N a + 3N 2
Chemical Properties of Nitrogen
Nitrogen is a nonmetal with an electronegativity of 3.04. It has five electrons in its outer shell
and is, therefore, trivalent in most compounds. The triple bond in molecular nitrogen (N2) is
one of the strongest known. The resulting difficulty of converting N2 into other compounds,
and the ease (and associated high energy release) of converting nitrogen compounds into
elemental N2, have dominated the role of nitrogen in both nature and human economic
activities.
Nitrogen Emission Spectrum
Molecular nitrogen (14N2) is largely transparent to infrared and visible radiation because it is
a homonuclear molecule and, therefore, has no dipole moment to couple the electromagnetic
radiation at these wavelengths. Significant absorption occurs at extreme ultraviolet
wavelengths, beginning at a wavelength of around 100 nanometers. This is associated with
electronic transitions in the molecule to states in which charge is not distributed evenly
between nitrogen atoms. Nitrogen absorption leads to significant absorption of ultraviolet
radiation in the Earth's upper atmosphere and the atmospheres of other planetary bodies.
Spectrum of Nitrogen
Sending an electric current through nitrogen excites the electrons to higher energy levels. When they fall
to lower energy levels, certain frequencies of light (based on the difference in energy of the energy levels)
are observed, as shown.
Applications of Nitrogen Gas
Nitrogen gas has a variety of applications, including:
As an inert replacement for air where oxidation is undesirable
As a modified atmosphere, pure or mixed with carbon dioxide, to preserve the freshness
of packaged or bulk foods
In ordinary incandescent light bulbs as an inexpensive alternative to argon
In production of electronic parts such as transistors, diodes, and integrated circuits
Filling automotive and aircraft tires due to its inertness and lack of moisture or oxidative
qualities, as compared to air
As a propellant for draft wine, and as an alternative to or in combination with carbon
dioxide in carbonated beverages
Nitrogen is also used in preparing samples for chemical analysis to concentrate
and reduce the volume of liquid samples. Directing a pressurized stream of nitrogen gas
perpendicular to the surface of the liquid allows the solvent to evaporate while leaving the
solute(s) and unevaporated solvent behind. Nitrogen tanks are also replacing carbon dioxide
as the main power source for paintball guns. But, nitrogen must be kept at higher pressure
than CO2, making N2 tanks heavier and more expensive.