Nitrogen
Nitrogen is a chemical Carbon - Nitrogen - Oxygen
element in the periodic
table that has the symbol Ê
N and atomic number 7. A N
common normally PÊÊ
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
acid, and cyanides. Appearance colorless
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
Notable Characteristics Physical Properties
State of matter gas (__)
Nitrogen is a non-metal,
with an electronegativity Melting point 63.14 K (-345.75 ¡F)
of 3.0. It has five Boiling point 77.35 K (-320.17 ¡F)
electrons in its outer
shell, so is trivalent in Molar volume 13.54 ×10-3 m3/mol
most compounds. Pure Heat of vaporization 2.7928 kJ/mol
nitrogen is an unreactive Heat of fusion 0.3604 kJ/mol
colorless diatomic gas at
room temperature, and Vapor pressure __ Pa at __ K
comprises about 78% of Speed of sound 334 m/s at 298.15 K
the Earth's atmosphere.
It condenses at 77 K and Miscellaneous
freezes at 63 K. Liquid Electronegativity 3.04 (Pauling scale)
nitrogen is a common Specific heat capacity 1040 J/(kg*K)
cryogen.
Electrical conductivity __ 106/m ohm
Applications Thermal conductivity 0.02598 W/(m*K)
The greatest single 1st ionization potential 1402.3 kJ/mol
commercial use of 2nd ionization potential 2856 kJ/mol
nitrogen is as a
component in the 3rd ionization potential 4578.1 kJ/mol
manufacture of ammonia
via the Haber process. 4th ionization potential 7475.0 kJ/mol
Ammonia is subsequently 5th ionization potential 9444.9 kJ/mol
used for fertilizer
production and to produce 6th ionization potential 53266.6 kJ/mol
nitric acid. Nitrogen is 7th ionization potential 64360 kJ/mol
used as an inert
atmosphere in tanks of Most Stable Isotopes
explosive liquid storage
tanks, during production iso NA half-life DM DE MeV DP
of electronic parts such 13N {syn.} 9.965 m e capture 2.220 13C
as transistors, diodes,
and integrated circuits, 14N 99.634% N is stable with 7 neutrons
and is used in the 15N 0.366% N is stable with 8 neutrons
manufacture of stainless
steel. Nitrogen is used SI units & STP are used except where noted.
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.
