| Revision as of 04:57, 6 March 2006 view sourceTawkerbot2 (talk | contribs)131,306 editsm vandalism - reverted to 42066804 by Edgar181← Previous edit |
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ebony and jess were ere sayin that oxygen is just another science thing LOL n and we r also ere 2 say hi 2 every1 who reads this and who lyks what we wrote hehehehe |
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{{otheruses}} |
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{{Elementbox_header | number=8 | symbol=O | name=oxygen | left=] | right=] | above=- | below=] | color1=#a0ffa0 | color2=green }} |
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{{Elementbox_series | ]s }} |
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{{Elementbox_groupperiodblock | group=16 | period=2 | block=p }} |
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{{Elementbox_appearance_img | O,8| colorless }} |
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{{Elementbox_atomicmass_gpm | ]] }} |
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{{Elementbox_econfig | 1s<sup>2</sup> 2s<sup>2</sup> 2p<sup>4</sup> }} |
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{{Elementbox_epershell | 2, 6 }} |
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{{Elementbox_section_physicalprop | color1=#a0ffa0 | color2=green }} |
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{{Elementbox_phase | ] }} |
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{{Elementbox_density_gplstp | 1.429 }} |
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{{Elementbox_meltingpoint | k=54.36 | c=-218.79 | f=-361.82 }} |
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{{Elementbox_boilingpoint | k=90.20 | c=-182.95 | f=-297.31 }} |
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{{Elementbox_heatfusion_kjpmol | (O<sub>2</sub>) 0.444 }} |
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{{Elementbox_heatvaporiz_kjpmol | (O<sub>2</sub>) 6.82 }} |
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{{Elementbox_heatcapacity_jpmolkat25 | (O<sub>2</sub>)<br />29.378 }} |
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{{Elementbox_vaporpressure_katpa | | | | 61 | 73 | 90 | comment= }} |
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{{Elementbox_section_atomicprop | color1=#a0ffa0 | color2=green }} |
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{{Elementbox_crystalstruct | cubic }} |
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{{Elementbox_oxistates | −'''2''', −1<br />(neutral oxide) }} |
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{{Elementbox_electroneg_pauling | 3.44 }} |
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{{Elementbox_ionizationenergies4 | 1313.9 | 3388.3 | 5300.5 }} |
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{{Elementbox_atomicradius_pm | ] }} |
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{{Elementbox_atomicradiuscalc_pm | ] }} |
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{{Elementbox_covalentradius_pm | ] }} |
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{{Elementbox_vanderwaalsrad_pm | ] }} |
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{{Elementbox_section_miscellaneous | color1=#a0ffa0 | color2=green }} |
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{{Elementbox_magnetic | ] }} |
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{{Elementbox_thermalcond_wpmkat300k | 26.58 m}} |
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{{Elementbox_speedofsound_mps | (gas, 27 °C) 330 }} |
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{{Elementbox_cas_number | 7782-44-7 }} |
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{{Elementbox_isotopes_begin | isotopesof=oxygen | color1=#a0ffa0 | color2=green }} |
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{{Elementbox_isotopes_stable | mn=16 | sym=O | na=99.762% | n=8 }} |
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{{Elementbox_isotopes_stable | mn=17 | sym=O | na=0.038% | n=9 }} |
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{{Elementbox_isotopes_stable | mn=18 | sym=O | na=0.205% | n=10 }} |
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{{Elementbox_isotopes_end}} |
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{{Elementbox_footer | color1=#a0ffa0 | color2=green }} |
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'''Oxygen''' is a ] in the ]. It has the symbol '''O''' and ] 8. The element is the second most common on ], composing around 46% of the mass of Earth's crust and 28% of the mass of Earth as a whole, and is the third most common element in the ]. On Earth, it is usually ] with other elements. Unbound oxygen (usually called molecular oxygen, O<sub>2</sub>, a ]) first appeared on Earth during the ] era (between 2500 million years ago and 1600 million years ago) and as a product of the ] action of early ]s (] and ]). The presence of free oxygen drove most of the organisms then living to extinction. The atmospheric abundance of free oxygen in later geological epochs and up to the present has been largely driven by ] organisms, roughly three quarters by ] and ] in the oceans and one quarter from terrestrial ]s. |
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== Characteristics == |
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At standard temperature and pressure, oxygen exists as a diatomic molecule with the formula O<sub>2</sub>, in which the two oxygen atoms are doubly bonded to each other. In its most stable form, oxygen exists as a diradical (]). Though radicals are commonly associated with highly reactive compounds, triplet oxygen is surprisingly (and fortunately) unreactive towards most compounds. ], a name given to several higher energy species in which all the electron spins are paired, is much more reactive towards common organic molecules. ] effectively absorb energy from singlet oxygen and convert it back into the unexcited ground state. |
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Oxygen is a major component of air, produced by plants during ], and is necessary for aerobic respiration in animals. The word ''oxygen'' derives from two words in ], ''οξυς (oxys)'' (acid, sharp) and ''γεινομαι (geinomai)'' (engender). The name "oxygen" was chosen because, at the time it was discovered in the late 18th century, it was believed that all acids contained oxygen. The ] has since been revised to not require oxygen in the molecular structure. |
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] and solid O<sub>2</sub> have a light blue color and both are highly ]. Liquid O<sub>2</sub> is usually obtained by the ] of liquid air. |
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Liquid and solid O<sub>3</sub> (]) have a deeper color of blue. |
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A recently discovered ] of oxygen, ] (O<sub>4</sub>), is a deep red solid that is created by pressurizing O<sub>2</sub> to the order of 20 GPa. Its properties are being studied for use in ] and similar applications, as it is a much more powerful oxidizer than either O<sub>2</sub> or O<sub>3</sub>. |
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== Applications == |
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Liquid oxygen finds use as an oxidizer in ] propulsion. Oxygen is essential to ], so oxygen supplementation has found use in ] (as ]). People who climb ]s or fly in ]s sometimes have supplemental oxygen supplies (as air). Oxygen is used in ] (such as the ] torch), and in the making of ] and ]. |
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Oxygen presents two ] centered in 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 ] from the vegetation's ], which is much weaker. The measurement presents several technical difficulties due to the low ] and due to the vegetation's architecture, but it has been proposed as a possibility to monitor the ] from satellites on a global scale. |
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Oxygen, as a mild euphoric, has a history of recreational use that extends into modern times. ]s can be seen at parties to this day. In the 19th century, oxygen was often mixed with ] to promote an ] effect; indeed, such a mixture (]) is commonly used in medicine today. |
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== History == |
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Oxygen was first discovered by ], Polish ] and ] in late 16th century. Sędziwój assumed the existence of oxygen by warming ] (saltpeter). He thought of the gas given off as "the elixir of life". |
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Oxygen was again discovered by the ] pharmacist ] sometime before 1773, but the discovery was not published until after the independent discovery by ] on ], ], who called the gas ''dephlogisticated air'' (see ]). Priestley published his discoveries in ] and Scheele in ]; consequently Priestley is usually given the credit. It was named by ] after Priestley's publication in 1775. |
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== Occurrence == |
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Oxygen is the most common component of the Earth's crust (46.6% by mass), the second most common component of the Earth as a whole (28.2% by mass), and the second most common component of the Earth's atmosphere (20.947% by volume). |
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== Compounds == |
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] |
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Due to its ], oxygen forms ]s with almost all other elements hence the origin of the original definition of ]. The only elements to escape the possibility of oxidation are a few of the noble gases. The most famous of these oxides is dihydrogen monoxide, or ] (H<sub>2</sub>O). Other well known examples include compounds of carbon and oxygen, such as ] (CO<sub>2</sub>), ]s (R-OH), ]s, (R-CHO), and ]s (R-COOH). Oxygenated ]s such as ]s (ClO<sub>3</sub><sup>−</sup>), ]s (ClO<sub>4</sub><sup>−</sup>), ]s (CrO<sub>4</sub><sup>2−</sup>), ]s (Cr<sub>2</sub>O<sub>7</sub><sup>2−</sup>), ]s (MnO<sub>4</sub><sup>−</sup>), and ]s (NO<sub>3</sub><sup>−</sup>) are strong oxidizing agents in and of themselves. Many metals such as iron bond with oxygen atoms, ] (Fe<sub>2</sub>O<sub>3</sub>). ] (O<sub>3</sub>) is formed by electrostatic discharge in the presence of molecular oxygen. A double oxygen molecule (O<sub>2</sub>)<sub>2</sub> is known and is found as a minor component of liquid oxygen. ]s are ]s in which the oxygen atom is part of a ring of three atoms. |
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One unexpected oxygen compound is ] O<sub>2</sub><sup>+</sup>PtF<sub>6</sub><sup>−</sup>, which resulted when someone tried to make neutral ] in the presence of atmospheric air. This led to ] being made. |
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== Isotopes == |
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Oxygen has fifteen known isotopes with atomic masses ranging from 12 to 26. Three of them are stable and twelve are radioactive. The radioisotopes all have half lives of less than three minutes. The stable isotopes have mass numbers of 16, 17 and 18, of which <sup>16</sup>O is the most common (over 99%). |
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== Precautions == |
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Oxygen can be ] at elevated ]s (i.e. high relative concentrations). This is important in some forms of ] diving, such as with a ]. |
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Certain derivatives of oxygen, such as ] (O<sub>3</sub>), ], ], ]s and ], are also highly toxic. The body has developed mechanisms to protect against these toxic species. For instance, the naturally-occurring ] can act as an antioxidant, as can ] which is normally a breakdown product of ]. To protect against the destructive nature of peroxides, nearly every organism on earth has developed some form of the enzyme ], which very quickly ] peroxide into water and dioxygen. |
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Highly concentrated sources of oxygen promote rapid ] and therefore are ] and ] hazards in the presence of ]s. The fire that killed the ] crew on a test launchpad spread so rapidly because the capsule was pressurized with pure oxygen as would be usual in an actual flight, but to maintain positive pressure in the capsule, this was at slightly more than atmospheric pressure instead of the 1/3 pressure that would be used in flight. (See ].) Similar hazards also apply to compounds of oxygen with a high oxidative ''potential'', such as chlorates, perchlorates, and dichromates; they also can often cause chemical ]. |
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Oxygen derivatives are prone to form ], especially in metabolic processes. Because they can cause severe damage to cells and their ], they are thought to be related to cancer and aging. |
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== See also == |
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* ] for instructions on how to determine the amount of oxygen ]d in fresh water. |
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* ] |
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* ] |
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* ] in geology |
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* The role of oxygen as a diving ] |
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* ] aquatic ecology |
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* ] |
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==References== |
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*: Chart of the Nuclides, General Electric Company, 1989 |
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== External links == |
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{{Commons|Oxygen}} |
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