Nitrogen was isolated by the British physician
Daniel Rutherford in 1772 and recognized as an
elemental gas by the French chemist Antoine
Laurent Lavoisier about 1776. Properties
Nitrogen is a colorless, odorless, tasteless,
nontoxic gas. It can be condensed into a colorless
liquid, which can in turn be compressed into a
colorless, crystalline solid. Nitrogen exists in two
natural forms of isotopes, and four radioactive
isotopes have been artificially prepared. Nitrogen
melts at -210.01° C (-346.02° F), boils at
-195.79° C (-320.42° F), and has a density of
1.251 g/liter at 0° C (32° F). The atomic weight of
nitrogen is 14.007. Nitrogen is obtained from the
atmosphere by passing air over heated copper or
iron. The oxygen is removed from the air, leaving
nitrogen mixed with some inert gases. Pure
nitrogen is obtained by partial evaporation of liquid
air because liquid nitrogen has a lower boiling
point than liquid oxygen, the nitrogen evaporates
off first and can be collected. Nitrogen composes
about four-fifths (78.03 percent) by volume of the
atmosphere. Nitrogen is inert and serves as a
diluent for oxygen in burning and respiration
processes. It is an important element in plant
nutrition certain bacteria in the soil convert
nitrogen from the atmosphere into a form, such as
nitrate, that can be absorbed by plants, a process
called nitrogen fixation. Nitrogen in the form of
protein is an important component of animal tissue.
The element occurs in the combined state in
minerals, of which saltpeter (KNO3) and Chile
saltpeter (NaNO3) are highly important products.
Nitrogen combines with other elements only at
very high temperatures or pressures. It is
converted to an active form by passing through an
electric discharge at low pressure. The nitrogen
produced is very active, combining with alkali
metals to form azides with the vapor of zinc,
mercury cadmium, and arsenic to form nitrides and
with many hydrocarbons to form nitriles. Activated
nitrogen returns to ordinary nitrogen in about one
minute.In the combined state nitrogen takes has
many reactions it forms so many compounds that a
systematic scheme of compounds containing
nitrogen in place of oxygen was created by the
American chemist Edward Franklin. In
compounds nitrogen exists in all the combination
capacity states between -3 and +5. Ammonia, and
hydroxylamine represent compounds in which the
combination capacity of nitrogen is -3, -2, and -1,
individually. Oxides of nitrogen represent nitrogen
in all the positive combination capacity states.
Uses Most of the nitrogen used in the chemical
industry is obtained by the fractional distillation of
liquid air. It is then used to synthesize ammonia.
From ammonia produced in this manner, a wide
variety of important chemical products are
prepared, including fertilizers, nitric acid, urea,
hydrazine, and amines. In addition, an ammonia
compound is used in the preparation of nitrous
oxide (N2O) a colorless gas popularly known as
laughing gas. Mixed with oxygen, nitrous oxide is
used as an anesthetic for some types of
surgery.Used as a coolant, liquid nitrogen has
found widespread application in the field of
cryogenics. With the recent advent of ceramic
materials that become superconductive at the
boiling point of nitrogen, the use of nitrogen as a
coolant is increasing.

Category: Science