Oxygen
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Oxygen is a chemical element in the periodic table that has the symbol O and atomic number 8. The element is common and ubiquitous, found not only on earth but throughout the universe. Free oxygen, as on earth, is thermodynamically unstable, but exists through the action of photosynthetic plants.
| General | |||||||||||||||||||||||||||||||
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| Name, Symbol, Number | Oxygen, O, 8 | ||||||||||||||||||||||||||||||
| Chemical series | nonmetals | ||||||||||||||||||||||||||||||
| Group, Period, Block | 16 (VI), 2 , p | ||||||||||||||||||||||||||||||
| Density, Hardness | 1.429 kg/m3(273K), NA | ||||||||||||||||||||||||||||||
| Appearance | colorless | ||||||||||||||||||||||||||||||
| Atomic | |||||||||||||||||||||||||||||||
| 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) | ||||||||||||||||||||||||||||||
| Crystal structure | cubic | ||||||||||||||||||||||||||||||
| Physical | |||||||||||||||||||||||||||||||
| State of matter | gas (paramagnetic) | ||||||||||||||||||||||||||||||
| Melting point | 50.35 K (-368.77 °F) | ||||||||||||||||||||||||||||||
| Boiling point | 90.18 K (-297.08 °F) | ||||||||||||||||||||||||||||||
| Molar volume | 17.36 ×10-3 m3/mol | ||||||||||||||||||||||||||||||
| Heat of vaporization | 3.4099 kJ/mol | ||||||||||||||||||||||||||||||
| Heat of fusion | 0.22259 kJ/mol | ||||||||||||||||||||||||||||||
| Vapor pressure | __ Pa at __ K | ||||||||||||||||||||||||||||||
| Velocity of sound | 317.5 m/s at 293 K | ||||||||||||||||||||||||||||||
| Miscellaneous | |||||||||||||||||||||||||||||||
| Electronegativity | 3.44 (Pauling scale) | ||||||||||||||||||||||||||||||
| Specific heat capacity | 920 J/(kg*K) | ||||||||||||||||||||||||||||||
| Electrical conductivity | __ 106/m ohm | ||||||||||||||||||||||||||||||
| Thermal conductivity | 0.02674 W/(m*K) | ||||||||||||||||||||||||||||||
| 1st ionization potential | 1313.9 kJ/mol | ||||||||||||||||||||||||||||||
| 2nd ionization potential | 3388.3 kJ/mol | ||||||||||||||||||||||||||||||
| 3rd ionization potential | 5300.5 kJ/mol | ||||||||||||||||||||||||||||||
| 4th ionization potential | 7469.2 kJ/mol | ||||||||||||||||||||||||||||||
| Most Stable Isotopes | |||||||||||||||||||||||||||||||
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| SI units & STP are used except where noted. | |||||||||||||||||||||||||||||||
Notable Characteristics
At standard temperature and pressure, oxygen is found as a gas consisting of two oxygen atoms, chemical formula O2. This oxygen is an important component of air, produced by plants during photosynthesis and is necessary for animals' respiration. The word oxygen derives from two words in Greek, the Greek oxus (acid) and gennan (generate).
Liquid oxygen and solid oxygen have a light blue color and both are highly paramagnetic.
Applications
Oxygen finds considerable use as an oxidizer. Liquid oxygen finds use as an oxidizer in rocket propulsion. Oxygen is essential to respiration, so oxygen supplementation has found use in medicine. People who climb mountains, scuba dive, 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 comprises about 87% of the oceans (as H2O, water) and 20% of the atmosphere (as O2, molecular oxygen, or O3, ozone).
Compounds
Due to its electronegativity, oxygen easily forms chemical bonds with many other elements (which is the origin of the original definition of oxidation). The most famous of these compounds 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.
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. 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 explosion hazards in the presence of fuels. This is true as well of compounds of oxygen such as chlorates, perchlorates, dichromates, etc.
Information sources and external links:
Los Alamos National Laboratory - Oxygen
WebElements.com - Oxygen
EnvironmentalChemistry.com - Oxygen
Oxygen Therapy - The First 150 Years
Oxygen Toxicity
- See also combustion -- Oxidation.
- Back to Chemistry -- Periodic table
Oxygen is a Cable TV channel in the US. (since of 2001?) Its programming targets women audience.