Oxygen



Oxygen is a chemical
element in the periodic
table that has the symbol Ê
O and atomic number 8.
The element is common and
ubiquitous, found not
only on earth but         Ê

throughout the universe.                       General
Free oxygen, as on earth,
is thermodynamically      Name, Symbol, Number      Oxygen, O, 8
unstable, but exists      Chemical series           nonmetals
through the action of     Group, Period, Block      16 (VIA), 2 , p
photosynthetic plants.
                          Density, Hardness         1.429 kg/m3 (273K), NA
                          Appearance                colorless
                                              Atomic Properties

                          Atomic weight             15.9994 amu
                          Atomic radius (calc.)     60 (48) pm
                          Covalent radius           73 pm
                          van der Waals radius      152 pm
                          Electron configuration    [He]2p42s2

                          e- 's per energy level    2, 6

                          Oxidation states (Oxide)  -2,-1 (neutral)
Notable Characteristics   Crystal structure         cubic
                                         Physical Properties
At standard temperature   State of matter           gas (paramagnetic)
and pressure, oxygen is
found as a gas consisting Melting point             50.35 K (-368.77 ¡F)
of two oxygen atoms,      Boiling point             90.18 K (-297.08 ¡F)
chemical formula O2. This
                          Molar volume              17.36 ×10-3 m3/mol
oxygen is an important
component of air,         Heat of vaporization      3.4099 kJ/mol
produced by plants during Heat of fusion            0.22259 kJ/mol
photosynthesis and is
necessary for animals'    Vapor pressure            __ Pa at __ K
respiration. The word     Speed of sound            317.5 m/s at 293 K
oxygen derives from two                     Miscellaneous
words in Greek, the Greek
oxus (acid) and gennan    Electronegativity         3.44 (Pauling scale)
(generate).               Specific heat capacity    920 J/(kg*K)
Liquid oxygen and solid   Electrical conductivity   __ 106/m ohm
oxygen have a light blue  Thermal conductivity      0.02674 W/(m*K)
color and both are highly 1st ionization potential  1313.9 kJ/mol
paramagnetic. Liquid
oxygen is usually         2nd ionization potential  3388.3 kJ/mol
obtained by the
fractional distillation   3rd ionization potential  5300.5 kJ/mol
of liquid air.            4th ionization potential  7469.2 kJ/mol

                                          Most Stable Isotopes

Applications               iso    NA       half-life     DM   DE MeV    DP
                          16O  99.762%  O is stable with 8 neutrons
Oxygen finds considerable
use as an oxidizer, with  17O  0.038%   O is stable with 9 neutrons

only fluorine having a    18O  0.2%     O is stable with 10 neutrons
higher electronegativity.
Liquid oxygen finds use      SI units & STP are used except where noted.
as an oxidizer in rocket
propulsion. Oxygen is essential to respiration, so oxygen supplementation
has found use in medicine. People who climb mountains or fly in airplanes
generally have supplemental oxygen supplies. Oxygen is used in welding, and
in the making of steel and methanol.

Oxygen, as a mild euphoric, has a history of recreational use that extends
into modern times. Oxygen bars can be seen at parties to this day. In the
19th century, oxygen was often mixed with nitrous oxide to promote a kind of
analgesic effect.

History

Oxygen was discovered by the Swedish pharmacist Karl Wilhelm Scheele in
1771, but this discovery was not immediately recognized, and the independent
discovery by Joseph Priestley was more widely known. It was named by Antoine
Laurent Lavoisier in 1774.

Occurrence

Oxygen is the most abundant element in the earth's crust, estimated to
comprise 46.7% of the crust. Oxygen comprises about 87% of the oceans (as
H2O, water) and 20% of the atmosphere of Earth (as O2, molecular oxygen, or
O3, ozone). Oxygen compounds, particularly metal oxides, silicates (SiO44-)
and carbonates (CO32-), are commonly found in rocks and soil. Frozen water
is a common solid on the outer planets and comets. The ice caps of Mars are
made of frozen carbon dioxide. Oxygen compounds are found throughout the
universe and the spectrum of oxygen is often seen in stars. In fact stars
and wouldn't produce light without oxygen.

Compounds

Due to its electronegativity, oxygen forms chemical bonds with almost all
other elements (which is the origin of the original definition of
oxidation). The only elements to escape the possibility of oxidation are a
few inert gases. The most famous of these oxides is of course hydrogen
oxide, or water (H2O). Other well known examples include compounds of carbon
and oxygen, such as carbon dioxide (CO2), alcohols (R-OH), aldehydes,
(R-CHO), and carboxylic acids (R-COOH). Oxygenated radicals such as
chlorates (ClO3-), perchlorates (ClO4-), chromates (CrO42-), dichromates
(Cr2O72-), permanganates (MnO4-), and nitrates (NO3-)are strong oxidizing
agents in and of themselves. Many metals such as Iron bond with oxygen
atoms, Ferric Oxide (Fe2O3). Ozone (O3) is formed by electrostatic discharge
in the presence of molecular oxygen. A double oxygen molecule (O2)2 is
known, found as a minor component of liquid oxygen.

Isotopes

Oxygen has three stable isotopes and ten radioactive isotopes. The
radioisotopes all have half lives of less than three minutes.

Precautions

Prolonged exposure to pure oxygen at higher pressures can be toxic, having
both pulmonary and neurological effects. Pulmonary effects include edema,
loss of lung capacity and damage to lung tissues. Neurological effects can
include loss of vision, convulsions and coma.

Compounds of oxygen, such as ozone (O3), peroxide, and superoxide, are also
highly toxic. Highly concentrated sources of oxygen promote rapid combustion
and therefore are fire and explosion hazards in the presence of fuels. This
is true as well of compounds of oxygen such as chlorates, perchlorates,
dichromates, etc. Compounds with a high oxidative potential can often cause
chemical burns.

The fire that killed the Apollo 1 crew on a test lauchpad spread so rapidly
because the pure oxygen atmosphere was at normal atmospheric pressure
instead of the one third pressure that would be used during an actual launch.

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