Nitrogen

Nitrogen is a chemical
element in the periodic
table that has the symbol Ê
N and atomic number 7. A
common normally
colorless, odorless,
tasteless and mostly      Ê

inert diatomic non-metal                       General
gas, nitrogen constitutes
78 percent of earth's     Name, Symbol, Number      Nitrogen, N, 7
atmosphere and is a       Chemical series           nonmetals
constituent of all living Group, Period, Block      15 (VA), 2 , p
tissues. Nitrogen forms
many important compounds  Density, Hardness         1.2506 kg/m3(273K), NA
such as ammonia, nitric   Appearance                colorless
acid, and cyanides.
                                          Atomic Properties
                          Atomic weight             14.0067 amu
                          Atomic radius (calc.)     65 (56) pm
                          Covalent radius           75 pm
                          van der Waals radius      155 pm
                          Electron configuration    [He]2s22p3
                          e- 's per energy level    2, 5
                          Oxidation states (Oxide)  ±3,5,4,2 (strong acid)
                          Crystal structure         hexagonal
                                         Physical Properties
Notable Characteristics   State of matter           gas (__)
Nitrogen is a non-metal,  Melting point             63.14 K (-345.75 ¡F)
with an electronegativity Boiling point             77.35 K (-320.17 ¡F)
of 3.0. It has five
electrons in its outer    Molar volume              13.54 ×10-3 m3/mol
shell, so is trivalent in Heat of vaporization      2.7928 kJ/mol
most compounds. Pure      Heat of fusion            0.3604 kJ/mol
nitrogen is an unreactive
colorless diatomic gas at Vapor pressure            __ Pa at __ K
room temperature, and     Speed of sound            334 m/s at 298.15 K
comprises about 78% of
the Earth's atmosphere.                     Miscellaneous
It condenses at 77 K and  Electronegativity         3.04 (Pauling scale)
freezes at 63 K. Liquid   Specific heat capacity    1040 J/(kg*K)
nitrogen is a common
cryogen.                  Electrical conductivity   __ 106/m ohm
                          Thermal conductivity      0.02598 W/(m*K)
Applications
                          1st ionization potential  1402.3 kJ/mol

The greatest single       2nd ionization potential  2856 kJ/mol
commercial use of
nitrogen is as a          3rd ionization potential  4578.1 kJ/mol
component in the
manufacture of ammonia    4th ionization potential  7475.0 kJ/mol

via the Haber process.    5th ionization potential  9444.9 kJ/mol
Ammonia is subsequently
used for fertilizer       6th ionization potential  53266.6 kJ/mol

production and to produce 7th ionization potential  64360 kJ/mol
nitric acid. Nitrogen is
used as an inert                         Most Stable Isotopes
atmosphere in tanks of
explosive liquid storage   iso    NA    half-life       DM      DE MeV  DP
tanks, during production  13N  {syn.}   9.965 m     e capture  2.220   13C
of electronic parts such
as transistors, diodes,   14N  99.634%  N is stable with 7 neutrons

and integrated circuits,  15N  0.366%   N is stable with 8 neutrons
and is used in the
manufacture of stainless     SI units & STP are used except where noted.
steel. Nitrogen is used
as a coolant both for the immersion freezing of food products and for
transportation of foods, for the preservation of bodies and reproductive
cells (sperm and egg), and for the stable storage of biological samples in
biology.

The salts of nitric acid include some important compounds, for example
potassium nitrate, or saltpeter, and ammonium nitrate. The former compound
is a component of gunpowder, the latter important in fertilizer. Nitrated
organic compounds, such as nitroglycerin and trinitrotoluene, are often
explosives.

Nitric acid is used as an oxidizer in liquid fueled rockets. Hydrazine and
hydrazine derivatives find use as rocket fuels.

Nitrogen in its liquid state (often referred to as LN2) is often used in
cryogenics. Liquid nitrogen is produced by distillation from liquid air. At
atmospheric pressure, nitrogen condenses at -195.8 degrees Celsius. (-320.4
degrees Fahrenheit).

History

Nitrogen (Latin nitrum, Greek Nitron meaning "native soda", "genes",
"forming") is formally considered to have been discovered by Daniel
Rutherford in 1772, who called it noxious air. That there was a fraction of
air that did not support combustion was well known to the late 18th century
chemist. Nitrogen was also studied at about the same time by Carl Wilhelm
Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt
air or dephilogisticated air. Nitrogen gas was inert enough that Antoine
Lavoisier referred to it as azote, which stands for without life.

Compounds of nitrogen were known in the Middle Ages. The alchemists knew
nitric acid as aqua fortis. The mixture of nitric and hydrochloric acids was
known as aqua regia, celebrated for its ability to dissolve gold.

Occurrence

Nitrogen is the largest single component of the Earth's atmosphere (78.1% by
volume) and is acquired for industrial purposes by the fractional
distillation of liquid air.. Compounds that contain this element have been
observed in outer space. Nitrogen-14 is created as part of the fusion
processes in stars. Nitrogen is a large component of animal waste (for
example, guano), usually in the form of urea, uric acid, and compounds of
these nitrogenous products.

Compounds

The main hydride of nitrogen is ammonia (NH3) although hydrazine (N2H4) is
also well known. Ammonia is somewhat more basic than water, and in solution
forms ammonium ions (NH4+). Liquid ammonia in fact slightly amphiprotic and
forms ammonium and amide ions (NH2-); both amides and nitride (N3-) salts
are known, but decompose in water. Singly and doubly substituted compounds
of ammonia are called amines. Larger chains, rings and structures of nitogen
hydrides are also known but virtually unstable.

Other classes of nitrogen anions are azides (N3-), which are linear and
isoelectronic to carbon dioxide. Another molecule of the same structure is
dinitrogen monoxide (N2O), or laughing gas. This is one of a variety of
oxides, the most prominent of which are nitrogen monoxide (NO) and nitrogen
dioxide (NO2), which both contain an unpaired electron. The latter shows
some tendency to dimerize and is an important component of smog.

The more standard oxides, dinitrogen trioxide (N2O3) and dinitrogen
pentoxide (N2O5), are actually fairly unstable and explosive. The
corresponding acids are nitrous (HNO2) and nitric acid (HNO3), with the
corresponding salts called nitrites and nitrates. Nitric acid is one of the
few acids stronger than hydronium.

Biological Role

Nitrogen is an essential part of amino and nucleic acids which makes
nitrogen vital to all life. Legumes like the soybean plant, can recover
nitrogen directly from the atmosphere because their roots have nodules
harboring microbes that do the actual conversion to ammonia in a process
known as nitrogen fixation. The legume subsequently converts ammonia to
nitrogen oxides and amino acids to form proteins.

Isotopes

There are two stable isotopes: N-14 and N-15. By far the most common is N-14
(99.634%), which is produced in the CNO cycle in stars. The rest is N-15. Of
the ten isotopes produced synthetically, one has a half life of nine minutes
and the remaining isotopes have half lives on the order of seconds or less.
Biologically-mediated reactions (e.g., assimilation, nitrification, and
denitrification) strongly control nitrogen dynamics in the soil. These
reactions almost always result in N-15 enrichment of the substrate and
depletion of the product. Although precipitation often contains subequal
quantities of ammonium and nitrate, because ammonium is preferentially
retained by the canopy relative to atmospheric nitrate, most of the
atmospheric nitrogen that reaches the soil surface is in the form of
nitrate. Soil nitrate is preferentially assimilated by tree roots relative
to soil ammonium.

Precautions

Nitrate fertilizer washoff is a major source of ground water and river
pollution. Cyano (-CN) containing compounds form extremely poisonous salts
and are deadly to many animals and all mammals.

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