| For other uses, see O (disambiguation).Look up O, o in Wiktionary, the free dictionary.This Semitic letter in its original form seems to have been inspired by a similar Egyptian hieroglyph for "eye".In Greek, a variation of the form later came to distinguish this long sound (Omega, meaning "large O") from the short o (Omicron, meaning "small o").Its graphic form has also remained fairly constant from Phoenician times until today.Indeed, even alphabets constructed "from scratch", i.Afaka and Ol Chiki scripts, each invented in different parts of the world in the last century, both attributed their vowels for 'O' to the shape of the mouth when making this sound.This form is colloquially termed the "long o" in English, but the sound used for it is actually different.In English there is also a "short O", which also has several pronunciations.When the vowel is unstressed, its pronunciation often drops back to an open front unrounded vowel (a).The Russian language has a similar unstressed form for its equivalent letter O, which looks the same.OA, OE, and OU represent a variety of pronunciations depending on context and etymology.Other languages use O for various values, usually back vowels which are at least partly open.Latin and Greek, particularly rounded front vowels.In Unicode the capital O is codepoint U+004F and the lowercase o is U+006F.The ASCII code for capital O is 79 and for lowercase o is 111; or in binary 01001111 and 01101111, correspondingly.The EBCDIC code for capital O is 214 and for lowercase o is 150.Meanings of O
See O (disambiguation).This page was last modified 19:15, 30 December 2007.All text is available under the terms of the GNU Free Documentation License.See Copyrights for details.Standard atomic weight
15.Heat of fusion
(O2) 0.Heat of vaporization
(O2) 6.Ionization energies
(more)
1st: 1313.Thermal conductivity
(300 K) 26.For other uses, see Oxygen (disambiguation).It is a chalcogen, period 2, nonmetallic element that can form binary compounds (known as oxides) with almost all the other elements.On Earth, oxygen is usually bonded to other elements covalently or ionically.Free diatomic oxygen or dioxygen (O2) is, together with nitrogen, one of the two major components of air, constituting about a fifth of the volume of air.Oxygen is highly reactive, and readily forms compounds with most other elements.Its compounds with silicon and metals are abundant in the earth's crustal rocks and with hydrogen in water (H2O).The nucleic acids and all of the major classes of structural molecules in living organisms, proteins, polysaccharides, and fats contain oxygen, as do the major inorganic compounds that comprise animal shell (calcium carbonate), and tooth and bone (calcium phosphate).Without oxygen, most organisms with aerobic respiration die within minutes.However, free oxygen is toxic to obligate anaerobic organisms and was a poisonous waste product for early life on Earth.Isotopes and stellar origin
1.Geologic timeline of biosynthesis
3.Oxygen uptake and transport
3.In human history
4.Life support and recreational use
6.See also
9 Notes
9.At standard temperature and pressure, oxygen is a colorless, odorless gas with the molecular formula O2, in which the two oxygen atoms are chemically bonded to each other with a triplet electron configuration.This bond has a bond order of two, and is often simplified in description as a double bond.The molecular orbital diagram of dioxygen (middle) in the ground triplet state.Triplet oxygen is the ground state of the oxygen molecule.The electron configuration of the molecule has two unpaired electrons occupying two degenerate molecular orbitals.These orbitals are classified as antibonding (weakening the bond order from three to two), so the diatomic oxygen bond is weaker than the diatomic nitrogen triple bond in which all bonding molecular orbitals are filled, but fewer antibonding ones are.Though unpaired electrons are commonly associated with high reactivity in chemical compounds, triplet oxygen is relatively nonreactive by comparison with most radicals.In normal triplet form, oxygen molecules are paramagnetic due to the spin magnetic moments of the unpaired electrons in the molecule, and the negative exchange energy between neighboring O2 molecules.Liquid oxygen is attracted to a magnet to a sufficient extent that, in laboratory demonstrations, a bridge of liquid oxygen may be supported against its own weight between the poles of a powerful magnet.Oxygen's paramagnetism can be used analytically in paramagnetic oxygen gas analysers that determine the purity of gaseous oxygen.In nature, singlet oxygen is commonly formed from water during photosynthesis, using the energy of sunlight.Carotenoids in photosynthetic organisms (and possibly also in animals) play a major role in absorbing energy from singlet oxygen and converting it to the unexcited ground state before it can cause harm to tissues.Physical properties
Oxygen is more soluble in water than nitrogen, water containing approximately 1 part of oxygen to 2 of nitrogen, compared with a ratio in the atmosphere of approximately 1:4.Oxygen condenses at 90.Rayleigh scattering of blue light).Liquid oxygen may also be produced by condensation out of air, using liquid nitrogen as a coolant.Ozone is a rare gas on Earth found mostly in the stratosphere.The common allotrope of elemental oxygen on Earth O2, is called dioxygen.This article is primarily concerned with this allotrope.Triatomic oxygen (Ozone, O3), is a very reactive allotrope of oxygen that is damaging to lung tissue.Ozone is produced in the upper atmosphere when O2 combines with atomic oxygen made by the splitting of O2 with UV radiation.Ozone absorbs strongly in the ultraviolet and functions as a protective radiation shield for the planet (see ozone layer).O2 to 20 GPa.It is a much more powerful oxidizer than either O2 or O3 and may therefore be used in rocket fuel.When tetraoxygen is subjected to a pressure of 96 GPa, it becomes metallic, in a similar manner as hydrogen.Naturally occurring oxygen is composed of 3 stable isotopes, 16O, 17O, and 18O, with 16O being the most abundant (99.Oxygen isotopes range in mass number from 12 to 28.Most 16O is synthesized at the end of the helium fusion process in stars but some is made in the neon burning process.CNO cycle, making it a common isotope in the hydrogen burning zones of stars.The most common decay mode before the stable isotopes is electron capture and the most common mode after is beta decay.The decay products before the stable isotopes are element 7 (nitrogen) isotopes and the products after are element 9 (fluorine) isotopes.Category:Oxide minerals
Oxygen is the third most abundant chemical element in the universe, after hydrogen and helium.Sun's mass is in the form of oxygen.Earth's atmosphere, taking up 20.Earth is unusual in having such a high concentration of free oxygen in its atmosphere.Venus comes in third place.Cold water holds more dissolved oxygen.The unusually high concentration of elemental oxygen on Earth is the result of the oxygen cycle.This biogeochemical cycle describes the movement of oxygen within and between its three main reservoirs on Earth: the atmosphere, the biosphere, and the lithosphere.The main driving factor of the oxygen cycle is photosynthesis, which is responsible for modern Earth's atmosphere.Because of the vast amounts of oxygen in the atmosphere, even if all photosynthesis were to cease, it would take at least 5,000 years to strip out more or less all oxygen.Free elemental dioxygen also occurs in solution in the world's water bodies.The higher solubility of O2 at low temperatures (see Physical Properties) has important implications for ocean life, as polar oceans support a much higher density of life due to their higher oxygen content.Polluted water may have reduced amounts of oxygen in it, depleted by decaying algae and other biomaterials (see eutrophication).Scientists assess this aspect of water quality by measuring the water's biochemical oxygen demand (BOD), or the amount of oxygen needed to restore a normal oxygen concentration.Oxygen as a compound is present in the atmosphere in trace quantities in the form of carbon dioxide (CO2).The earth's crustal rock is composed predominantly of oxides of silicon as silica, SiO2 (found in granite and sand), silicates (found in feldspars), and oxygen compounds of metals such as calcium (as calcium carbonate in limestone), aluminium (as silicates in feldspars and as aluminium oxide in bauxite and corundum), iron (as iron (III) oxide Fe2O3 in hematite and rust), etc.Silica is the common name for the compound silicon dioxide (SiO2).Na4SiO4, Na2SiO3, and Na2Si2O5 are used as detergents and adhesives.NaxSixOx with a higher ratio of SiO2 to Na2O has a greater molecular weight and a lower solubility.Pm2O3) and neptunium (NpO2); and also with some of the least reactive elements such as xenon (XeO3), gold (Au2O3) and platinum (PtO2).Synthetic elements that have known oxides include plutonium (PuO2), americium (AmO2), curium (CuO2), berkelium (BkO3), californium (Cf2O3) and einsteinium (Es2O3).Oxygen forms heteropoly acids and polyoxometalate ions with tungsten, molybdenum and some other transition metals.Phosphotungstic acid (PTA), or dodecatungstophosphoric acid, has the chemical formula H3PW12O40, while octadecamolybdophosphoric acid is H6P2Mo18O62.Neil Bartlett was studying the properties of platinum hexafluoride (PtF6).He noticed a change in color when this compound was exposed to atmospheric air and reasoned that xenon should be oxidized by PtF6.The cation O22+ in O2F2 is only formed in the presence of stronger oxidants than oxygen, which limits it to oxygen fluorides, e.When dissolved in water, many metallic oxides form alkaline solutions while many oxides of nonmetals form acidic solutions.For example, sodium oxide in solution forms the strong base sodium hydroxide while phosphorus pentoxide in solution forms phosphoric acid.Water (H2O) is the oxide of hydrogen and the most familiar oxygen compound.Its bulk properties partly result from the interaction of its component atoms, oxygen and hydrogen, with atoms of nearby water molecules.Hydrogen atoms are covalently bonded to oxygen in a water molecule but also have an additional attraction (about 23.Van der Waals forces.Due to its electronegativity, oxygen forms chemical bonds with almost all other free elements at elevated temperatures to give corresponding oxides.However, some elements, such as iron, readily forms iron oxide, or rust, Fe2O3 at standard conditions for temperature and pressure (STP).The surface of metals like aluminium and titanium are oxidized in the presence of air and become coated with a thin film of oxide that passivates the metal and slows further corrosion.III) oxide must be formed by an indirect route.The alkali metals and alkali earth metals all react spontaneously with oxygen when exposed to air to form oxides and form hydroxides in the presence of water.As a result, none of these elements are found in nature as free metals.Cesium is so reactive with oxygen that it is used as a getter in vacuum tubes.Although solid magnesium reacts slowly with oxygen at STP, it is capable of burning in air, generating very high temperatures, and its metal powder may form explosive mixtures with air.White or light yellow sodium peroxide (Na2O2) is formed when metallic sodium (Na) is burned in oxygen.Each oxygen atom in its peroxide ion may have a full octet of 4 pairs of electrons.These compounds form by oxidation of alkali metals with larger ionic radii (K, Rb, Cs).K) reacts with oxygen.Acetone is an important feeder material in the chemical industry.Oxygen is in red, carbon in black and hydrogen in white.There are many important organic solvents that contain oxygen, among which: acetone, methanol, ethanol, isopropanol, furan, THF, diethyl ether, dioxane, ethylacetate, DMF, DMSO, acetic acid, formic acid.Acetone ((CH3)2CO) and phenol (C6H5OH) are used as feeder materials in the synthesis of many different substances.Other important organic compounds that contain oxygen are: glycerol, formaldehyde, glutaraldehyde, citric acid, acetic anhydride, acetamide, etc.Epoxides are ethers in which the oxygen atom is part of a ring of three atoms.Oxygen reacts spontaneously with many organic compounds at or below room temperature in a process called autoxidation.Most of the organic compounds that contain oxygen are not made by direct action of oxygen.Biomolecules
DNA and proteins contain oxygen and the element is found in almost all biomolecules that are important to or generated by life.Of the organic compounds with biological relevance, carbohydrates (such as glucose) contain a large amount of oxygen.All fatty acids (such as oleic acid) and aminoacids contain oxygen (due to the presence of carboxyl group).ATP and ADP and in the backbone of RNA and DNA.Biological role
Oxygen plays an important role in the energy metabolism of living organisms.Oxygen evolution by water oxidation during photosynthesis.The remainder is produced by terrestrial plants, although almost all oxygen produced in tropical forests is consumed by organisms in those forests.H+ + O2
The reaction occurs in the thylakoid membranes of cyanobacteria and algal and plant chloroplasts and requires the energy of four photons.The protons from the oxidized water molecules are released into the thylakoid lumen, thus contributing to the generation of a proton gradient across the thylakoid membrane.This proton gradient is the driving force for ATP synthesis via photophosphorylation and coupling the absorption of light energy and photolysis of water to the creation of chemical energy during photosynthesis.The O2 remaining after oxidation of the water molecule is released into the atmosphere.Manganese is an important cofactor, and calcium and chloride are also required for the reaction to occur.Oxygen was almost nonexistent in Earth's atmosphere before the evolution of water oxidation in photosynthetic bacteria.Free oxygen first appeared in significant quantities during the Paleoproterozoic era (between 2.These organisms, fossil evidence for which occurs in the form of stromatolites and oncolites, developed the mechanism of oxygen evolution in the Archean era, between 3.At first, the produced oxygen dissolved in the oceans, where it was reduced by dissolved iron compounds, precipitating iron oxide (Fe2O3) and creating banded iron formations that are now a valuable resource of iron ore, hematite.The amount of oxygen in the atmosphere increased gradually at first and then more rapidly around 2.The presence of large amounts of dissolved and free oxygen in the oceans and atmosphere may have driven most of the anaerobic organisms then living to extinction during the oxygen catastrophe about 2.However, the high electronegativity of O2 creates a large potential energy drop for cellular respiration, thus enabling organisms using aerobic respiration to produce much more ATP than anaerobic organisms.This makes them so efficient that they have come to dominate Earth's biosphere.Photosynthesis and cellular respiration of oxygen allowed for the evolution of eukaryotic cells and ultimately complex multicellular organisms such as plants and animals.The atmospheric abundance of free oxygen in later geological epochs and its gradual increase up to the present has been largely due to synthesis by photosynthetic organisms.Human activities, including the burning of 7 billion tonnes of fossil fuels each year have had very little effect on the amount of free oxygen in the atmosphere.It was estimated that, at the current rate of photosynthesis, it would take about 2,000 years to regenerate the entire oxygen in the present atmosphere.In all vertebrates, the heme group of hemoglobin binds most of the oxygen dissolved in the blood.In vertebrates, oxygen uptake is carried out by the following processes:
Oxygen diffuses through membranes and into red blood cells after inhalation into the lungs.The heme group of hemoglobin binds oxygen when it is present, changing hemoglobin's color from bluish red to bright red.Vertebrate animals use hemoglobin in their blood to transport oxygen from their lungs to their tissues, but other animals use hemocyanin (molluscs and some arthropods) or hemerythrin (spiders and lobsters).Monooxygenase uses oxygen to catalyze many oxidation reactions in the body.Carbon dioxide, a waste product, is released from the cell and into the blood, where it combines with bicarbonate and hemoglobin for transport to the lungs.Blood circulates back to the lungs and the process repeats.Please help improve this article by expanding this section.See talk page for details.Please remove this message once the section has been expanded.See also: Aerobic respiration
Molecular oxygen, O2, is essential for cellular respiration in all aerobic organisms.Oxygen is used as an electron acceptor in mitochondria to generate chemical energy in the form of adenosine triphosphate (ATP) during oxidative phosphorylation.The body uses superoxide dismutase to reduce superoxide radicals to hydrogen peroxide.Glutathione peroxidase and similar enzymes then convert the H2O2 to water and dioxygen.Parts of the immune system of higher organisms, however, create peroxide, superoxide, and singlet oxygen to destroy invading microbes.This compound, in turn, disproportionates to ozone and peroxide, providing two powerful antibacterials.The body's range of defense against all of these active oxidizing agents is hardly surprising, then, given their "deliberate" employment as antimicrobial agents in the immune response.Reactive oxygen species also play an important role in the hypersensitive response of plants against pathogen attack.One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium.In his work Pneumatica, Philo observed that inverting a vessel over a burning candle and surrounding the vessel's neck with water resulted in some water rising into the neck.Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass.Many centuries later Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration.In the late 17th century, Robert Boyle proved that air is necessary for combustion.English chemist John Mayow refined this work by showing that fire requires only a part of air that he called 'spiritus nitroaereus' or just 'nitroaereus'.From this he surmised that nitroaereus is consumed in both respiration and combustion.Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it.He also thought that the lungs separate nitroaereus from air and pass it into the blood and that animal heat and muscle movement result from the reaction of nitroaereus with certain substances in the body.Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract "De respiratione".Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all also produced oxygen in experiments in the 17th century but none of them recognized it as an element.This was largely due to the prevalence of a philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of how those processes worked.Established in 1667 by German alchemist J.One part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, its calx.Air did not play a role in phlogiston theory, and no initial quantitative experiments were conducted to test the idea; instead, it was based on observations of what happened when something burns: that most common objects appear to become lighter and seem to lose something in the process.The fact that a substance like wood actually gains overall weight in burning was hidden by the buoyancy of the gaseous combustion products.That metals actually gain weight in rusting (when they were supposed to be losing phlogiston) was one of the first clues that the phlogiston theory is incorrect.An experiment conducted by the British clergyman Joseph Priestley on August 1, 1774 focused sunlight on mercuric oxide (HgO) inside a glass tube, which liberated a gas he named 'dephlogisticated air'.He noted that candles burned brighter in the gas and that a mouse was more active and lived longer while breathing it.After breathing the gas himself, he wrote: "The feeling of it to my lungs was not sensibly different from that of common air, but I fancied that my breast felt peculiarly light and easy for some time afterwards."Priestley published his findings in 1775 in a paper titled "An Account of Further Discoveries in Air" which was included in the second volume of his book titled Experiments and Observations on Different Kinds of Air.Because he published first, Priestley is usually given priority in the discovery.Unknown to Priestley, Swedish pharmacist Carl Wilhelm Scheele had already produced oxygen by heating mercuric oxide and various nitrates by about 1772.Scheele wrote an account of this discovery in a manuscript he titled Treatise on Air and Fire, which he sent to his publisher in 1775.However, that document was not published until 1777.Scheele called the gas 'fire air' because it was the only known supporter of combustion.Noted French chemist Antoine Laurent Lavoisier later claimed to have discovered the new substance independently.However, Priestley visited Lavoisier in October 1774 and told him about his experiment and how he liberated the new gas.Lavoisier never acknowledged receiving it (a copy of the letter was found in Scheele's belongings after his death).What Lavoisier did indisputably do was to conduct the first adequate quantitative experiments on oxidation and give the first correct explanation of how combustion works.He used these and similar experiments, all started in 1774, to discredit the Phlogiston theory and to prove that the substance discovered by Priestley and Scheele was a chemical element.In one experiment, Lavoisier observed that there was no overall increase in weight when tin and air were heated in a closed container.He noted that air rushed in when he opened the container, which indicated that part of the trapped air had been consumed.He also noted that the tin had increased in weight and that increase was the same as the weight of the air that rushed back in.This and other experiments on combustion were documented in his book Sur la combustion en general, which was published in 1777.In that work, he proved that air is a mixture of two gases; 'vital air', which is essential to combustion and respiration, and 'azote' (Gk.Oxygen entered the English language despite opposition by English scientists and the fact that Priestley had priority.This is partly due to a poem praising the gas titled "Oxygen" in the popular book The Botanic Garden (1791) by Erasmus Darwin, grandfather of Charles Darwin.Scientists realized by the late 19th century that compressing and cooling air could be used to liquefy and isolate its components.Using a cascade method, Swiss chemist and physicist Raoul Pierre Pictet evaporated liquid sulfur dioxide in order to liquefy carbon dioxide, which in turn was evaporated to cool oxygen enough to liquefy it.He sent a telegram on December 22, 1877 to the French Academy of Sciences in Paris announcing his discovery of liquid oxygen.Just two days later, French physicist Louis Paul Cailletet announced his own method of liquefying oxygen.Only a few drops of liquid oxygen were produced in either case so no meaningful analysis could be conducted.In 1891, Scottish chemist James Dewar was able to produce enough liquid oxygen to study.German engineer Carl von Linde and British engineer William Hampson.Both men lowered the temperature of air until it liquefied and then distilled the component gases by boiling them off one at a time and capturing them.Later, in 1901, oxyacetylene welding was demonstrated for the first time by burning a mixture of acetylene and compressed oxygen.This method of welding and cutting metal later became common.In 1923, American scientist Robert H.Goddard became the first person to develop a rocket engine; the engine used gasoline for fuel and liquid oxygen as the oxidizer.March 16, 1926 in Auburn, Massachusetts.Fractional distillation
Two major methods are employed to produce the 100 million tonnes of oxygen extracted from air for industrial uses annually.After a set cycle time, the operation of the two beds is switched, so that the producer bed is reverse purged and the purged bed becomes the producer bed.This allows for a continuous supply of gaseous oxygen to be pumped through a pipeline.It is known as pressure swing adsorption (PSA).Oxygen can also be produced through electrolysis of water into oxygen and hydrogen.Another air separation technology involves forcing air to dissolve through ceramic membranes based on zirconium oxide by either high pressure or an electric current, to produce nearly pure oxygen.Since the primary cost of production is the energy cost of liquefying the air, the production cost will change as energy cost varies.Such tankers are used to refill bulk liquid oxygen storage containers, which stand outside hospitals and other institutions with a need for large volumes of pure oxygen.Uptake of oxygen from the air is the essential purpose of respiration, so oxygen supplementation is used in medicine.Oxygen therapy is used to treat emphysema, pneumonia, some heart disorders, and any disease that impairs the body's ability to take up and use oxygen.Treatments are flexible enough to be used in hospitals, the patient's home, or increasingly by portable devices.Oxygen tents were once commonly used in oxygen supplementation, but have since been replaced mostly by the use of oxygen masks or nasal cannulas.Hyperbaric medicine uses hyperbaric oxygen chambers to increase the partial pressure of oxygen around the patient and, when needed, the medical staff.Carbon monoxide poisoning, gas gangrene, and decompression sickness (the "bends") are sometimes treated using these devices.Increased oxygen concentration in the lungs helps to displace carbon monoxide from the heme group of hemoglobin.Oxygen is poisonous to the anaerobic bacteria that cause gas gangrene, so increasing its partial pressure helps kill them.Decompression sickness occurs in divers who decompress too quickly after a dive, resulting in bubbles of inert gas, mostly nitrogen and argon, forming in their blood.Increasing the pressure of oxygen as soon as possible is part of the treatment.These devices use nearly pure oxygen at about one third normal pressure, resulting in a normal blood partial pressures of oxygen.Deeper diving requires significant dilution of oxygen with other gases, such as nitrogen or helium, to help prevent oxygen toxicity.Passengers traveling in commercial airplanes have an emergency supply of oxygen automatically supplied to them in case of cabin depressurization.Sudden cabin pressure loss activates chemical oxygen generators above each seat, causing oxygen masks to drop and forcing iron fillings into the sodium chlorate inside the canister.Oxygen, as a supposed mild euphoric, has a history of recreational use in oxygen bars and in sports.Oxygen bars are establishments, found in Japan, California and Las Vegas, Nevada since the late 1990s that offer higher than normal oxygen exposure for a fee.Professional athletes, especially in American football, also sometimes go off field between plays to wear oxygen masks in order to get a supposed "boost" in performance.However, the reality of a pharmacological effect is doubtful; a placebo or psychological boost being the most plausible explanation.Available studies support a performance boost from enriched oxygen mixtures only if they are breathed during actual aerobic exercise.Ethylene is reacted with oxygen to create ethylene oxide, which, in turn, is converted into ethylene glycol; the primary feeder material used to manufacture a host of products, including antifreeze and polyester polymers (the precursors of many plastics and fabrics).Oxygen is used in oxyacetylene welding burning acetylene with oxygen to produce a very hot flame.Rocket propulsion requires a fuel and an oxidizer.Larger rockets use liquid oxygen as their oxidizer, which is mixed and ignited with the fuel for propulsion.Paleoclimatologists also directly measure this ratio in the water molecules of ice core samples that are up to several hundreds of thousands of years old.Oxygen presents two spectrophotometric absorption bands peaking at the wavelengths 687 and 760 nanometers.Some scientists have proposed to use the measurement of the radiance coming from vegetation canopies in those oxygen bands to characterize plant health status from a satellite platform.This is because in those bands, it is possible to discriminate the vegetation's reflectance from the vegetation's fluorescence, which is much weaker.The measurement presents several technical difficulties due to the low signal to noise ratio and due to the vegetation's architecture, but it has been proposed as a possibility to monitor the carbon cycle from satellites on a global scale.Oxygen can be toxic at elevated partial pressures, leading to convulsions and other health problems.Breathing pure oxygen in space applications, such as in some modern spacesuits, or in early spacecraft such as Apollo, causes no damage due to the low total pressures used.Oxygen toxicity to the lungs and central nervous system can also occur in deep scuba diving and surface supplied diving.Pa can eventually lead to permanent pulmonary fibrosis.Pa leads to convulsions (normally fatal for divers).Fire and explosion hazards exist when concentrated oxidants and fuels are brought into close proximity; however, an ignition event, such as heat or a spark, is needed to trigger combustion.Oxygen itself is not the fuel, but an oxidant.Combustion hazards also apply to compounds of oxygen with a high oxidative potential, such as peroxides, chlorates, nitrates, perchlorates, and dichromates because they can donate oxygen to a fire.Concentrated oxygen will allow combustion to proceed rapidly and energetically.Steel pipes and storage vessels used to store and transmit both gaseous and liquid oxygen will act as a fuel; and therefore the design and manufacture of oxygen systems requires special training to ensure that ignition sources are minimized.Liquid oxygen spills, if allowed to soaked into organic matter, such as wood, petrochemicals, and asphalt can cause these materials to detonate unpredictably on subsequent mechanical impact.On contact with the human body, it can also cause cryogenic burns to the skin and the eyes.Hypoxia, a lack of oxygen
Hypoxia (environmental) for oxygen depletion in aquatic ecology
Optode for a method of measuring oxygen concentration in solution
Oxygen Catastrophe in geology
Oxygen isotope ratio cycle
Winkler test for dissolved oxygen for instructions on how to determine the amount of oxygen dissolved in fresh water.IUPAC Compendium of Chemical Terminology, 2, IUPAC.Los Alamos National Laboratory.Distribution of elements in the human body (by weight).The Internet Encyclopedia of Science.Structure of Oxygen Molecule (triplet).Demonstration of a bridge of liquid oxygen supported against its own weight between the poles of a powerful magnet.Madison Chemistry Department DEMONSTRATION LAB.Company literature of Oxygen analyzers (triplet)."Singlet oxygen production in photosynthesis.".Cambridge: Royal Society of Chemistry.Wentworth, Cindy Takeuchi, Jorge Nieva, Teresa Jones, Cristina Bautista, Julie M.Babior, Albert Eschenmoser, Richard A.Catalyzed Ozone Formation in Bacterial Killing and Inflammation"."Singlet oxygen quenching ability of naturally occurring carotenoids".Air solubility in water.Overview of Cryogenic Air Separation and Liquefier Systems.Liquid Oxygen Material Safety Data Sheet.Bond Lengths and Energies."Experimental Detection of Tetraoxygen"."NUCLEOSYNTHESIS AND GALACTIC CHEMICAL EVOLUTION OF THE ISOTOPES OF OXYGEN" in Workgroup on Oxygen in the Earliest Solar System.Proceedings of the NASA Cosmochemistry Program and the Lunar and Planetary Institute.From The Chemistry and Fertility of Sea Waters by H.Fox, "On the coefficients of absorption of atmospheric gases in sea water", Publ.Albert and Wilkinson, Geoffrey (1972).Advanced Inorganic Chemistry: A comprehensive Text.New York, London, Sydney, Toronto: Interscience Publications.Also, since oxygen has a higher electronegativity than hydrogen, the charge difference makes it a polar molecule.The interactions between the different dipoles of each molecule cause a net attraction force.The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodizing.Biology of Plants, 7th Edition."Marine Plants: A Unique and Unexplored Resource", Plants: the potentials for extracting protein, medicines, and other useful chemicals (workshop proceedings).Breathing easy, Et tu, O2.Biology of Plants, 7th Edition.Raval M, Biswal B, Biswal U (2005).Biological Science, 2nd Edition.Prentice Hall, 214, 586."Atmospheric oxygen over Phanerozoic time"."The Natural History of Oxygen"."The Story of O".Story of Human Error."John Mayow", Encyclopaedia Britannica, 11th edition.World of Chemistry contributors (2005)."John Mayow", World of Chemistry.The last sorcerers: The path from alchemy to the periodic table (Hardback), Washington, D."An Account of Further Discoveries in Air"."Oxygen", How Products are Made.The Gale Group, Inc.Cryogenic Air Separation Processes.National Transportation Safety Board.Oxygen Bars: Is a Breath of Fresh Air Worth It?.Food and Drug Administration.Progress on the development of an integrated canopy fluorescence model.Geoscience and Remote Sensing Symposium, 2003.Since oxygen partial pressure is the fraction of oxygen times the total pressure, elevated partial pressures can occur either from high oxygen fraction in breathing gas or from high breathing gas pressure, or a combination of both.ABC of oxygen: Diving and oxygen.Fire Hazards in Oxygen Systems.No single ignition source of the fire was conclusively identified, although some evidence points to arc from an electrical spark).Inviting Disaster: Lessons from the edge of Technology: An inside look at catastrophes and why they happen.New York: HarperCollins Publishers Inc."Carbon and Oxygen Nucleosynthesis in the Galaxy: Problems and Prospects".Maryland: Astronomical Society of the Pacific."Atmospheric oxygen over Phanerozoic time"."Oxygen", Matheson Gas Data Book."The Natural History of Oxygen"."Oxygen", in Clifford A.Hampel: The Encyclopedia of the Chemical Elements."Chapter 14: Oxygen", Advanced Inorganic Chemistry: A Comprehensive Text (3rd Edition).Biographical Encyclopedia of Scientists.Guide to the Elements.The Scientists:A History of Science Told Through the Lives of Its Greatest Inventors."Singlet oxygen quenching ability of naturally occurring carotenoids"."Singlet oxygen production in photosynthesis.".Mellor's Modern Inorganic Chemistry, 6th edition, London: Longmans, Green and Co.Guide to the Elements, Revised Edition, Oxford University Press."Yields from low metallicity, intermediate mass AGB stars: Their role for the CNO and lithium abundances in Globular Cluster stars".Wentworth, Cindy Takeuchi, Jorge Nieva, Teresa Jones, Cristina Bautista, Julie M.Ruedi, Abel Gutierrez, Kim D.Babior, Albert Eschenmoser, Richard A.Catalyzed Ozone Formation in Bacterial Killing and Inflammation".Look up oxygen in
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National leadership for O*NET development and implementation.SOC codes, or by browsing Job Families, High Growth industries, STEM disciplines, or O*NET Descriptors.Search results are displayed as a list of occupations ranked based on how well they matched the keywords.Select one of the descriptors to see a list of all elements or data items for that descriptor.Then select any element to view the occupations with available ratings for the selected element.Job Families are groups of occupations based upon work performed, skills, education, training, and credentials.Choose a family of occupations from the menu.Select an occupation title to view information about that occupation.National High Growth Industries are economically critical, projected to add substantial numbers of new jobs, and are being transformed by technology and innovation.Select an occupation title to view information about that occupation.Many occupations require education in science, technology, engineering, and mathematics (STEM) disciplines.Select a discipline to view the occupations requiring a STEM educational background.Then select an occupation title to view information about that occupation.Technology
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Learn more about the Occupational Information Network (O*NET).O*NET OnLine
A Web application for job seekers, employment professionals, and others interested in exploring occupations through O*NET.Resource Center
News and information about the O*NET program; and the source for O*NET products, including O*NET data, career exploration tools, and reports.Data Collection Program
The continuing data collection program to populate and update the O*NET database.Training and Awareness
Training, information sharing, and community building opportunities from the O*NET Knowledge Site.Department of Labor
National leadership for O*NET development and implementation.Welcome to O*NETTM OnLine!Making occupational information interactive
and accessible for all...Use STEM Disciplines to browse O*NET occupations.SOC codes, or by browsing Job Families, High Growth industries, STEM disciplines, or O*NET Descriptors.Learn about related skills important to employers and educators.The O*NET system serves as the nation's primary source of occupational information, providing comprehensive information on key attributes and characteristics of workers and occupations.The O*NET database houses this data and O*NET OnLine provides easy access to that information.Learn more about O*NET.Get the most out of OnLine with OnLine Help.If your search identifies occupations that require skills or abilities that may be difficult to use because of a health problem or disability, please consider job accommodations.O*NET OnLine was developed for the U.Department of Labor by the National Center for O*NET Development.For more information about the O*NET project, please visit the O*NET Resource Center.Technology
Send comments or inquiries to O*NET Information.About O*NET
Learn more about the Occupational Information Network (O*NET).O*NET OnLine
A Web application for job seekers, employment professionals, and others interested in exploring occupations through O*NET.Resource Center
News and information about the O*NET program; and the source for O*NET products, including O*NET data, career exploration tools, and reports.Data Collection Program
The continuing data collection program to populate and update the O*NET database.Training and Awareness
Training, information sharing, and community building opportunities from the O*NET Knowledge Site.Department of Labor
National leadership for O*NET development and implementation.About O*NET
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What's New?Welcome to the O*NETTM Resource Center, the nation's primary source of occupational information.Here you will find news and information about the O*NET program.This site is your source for O*NET products, including O*NET data, career exploration tools, and reports.Learn more in our O*NET Overview.O*NET OnLine is a Web application for job seekers, employment professionals, and others interested in exploring occupations through O*NET.Visit O*NET OnLine today!Find links to other helpful resources in Related Sites.For more details, visit the news archive.Have O*NET news delivered right to your inbox.Sign up for
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