Information AboutOxygen |
| CATEGORIES ABOUT OXYGEN | |
| chemical elements | |
| nonmetals | |
| chalcogens | |
| breathing gases | |
| oxygenchemical elements | |
| nonmetals | |
| chalcogens | |
| breathing gases | |
| oxygen | |
| chemical elements | |
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In with the chemical symbol O and Atomic Number 8. The word ''oxygen'' derives from two roots in Greek , ''οξύς (oxys)'' (acid, lit. sharp) and ''-γενής (-genēs)'' (producer, lit. begetter). It was recognized in 1777 by Antoine Lavoisier , who coined the name oxygen from the Greek roots mentioned above because he erroneously thought that it was a constituent of all acids. (The Definition Of Acid has since been revised). Oxygen has a Valency of 2. On Earth it is usually bonded to other elements Covalently or Ionically . Examples for common oxygen-containing compounds include Water (H2O), sand (silica, SiO2), and rust (iron oxide, Fe2O3). Diatomic oxygen (O2) is one of the two major components of Air (20.95%). It is produced by plants during Photosynthesis , and is necessary for Aerobic Respiration in animals. It is toxic to Obligate Anaerobic Organisms and was a poisonous waste product for early life on Earth . Triatomic oxygen ( Ozone , O3) forms through radiation in the upper layers of the atmosphere and acts as a shield against UV Radiation . CHARACTERISTICS . The phenomena are not related; the colour of the sky is due to Rayleigh Scattering .]] .]] The common allotrope of elemental oxygen on Earth, O2, is known as Dioxygen . At Standard Temperature And Pressure , oxygen exists as a diatomic Molecule with the formula O2, in which the two oxygen atoms are Bonded to each other with the Electron Configuration of Triplet Oxygen . This bond has a Bond Order of two, and is thus often very grossly simplified in description as a Double Bond .1 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 , so the diatomic oxygen bond is weaker than the diatomic Nitrogen bond, where all bonding molecular orbitals are filled. Though unpaired electrons are commonly associated with high reactivity in chemical compounds, triplet oxygen is relatively (and fortunately) nonreactive by comparison with most radicals. Singlet Oxygen , a name given to several higher energy species of molecular oxygen in which all the electron spins are paired, is much more reactive towards common Organic molecules. In nature, singlet oxygen is commonly formed from water during photosynthesis, using the energy of sunlight. It is also produced by the immune system as a source of active oxygen. 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. Liquid O2 and solid O2 are clear substances with a light sea-blue color. In normal triplet form they 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 a bridge of liquid oxygen may be supported against its own weight between the poles of a powerful magnet, in laboratory demonstrations. Liquid O2 is usually obtained by the Fractional Distillation of liquid air. Oxygen is slightly soluble in water, but naturally occurring dissolved amounts are enough to support animal life (see below). O2 has a bond length of 121 pm and a bond energy of 498 kJ/mol.2 Allotropes Ozone , the less common triatomic allotrope of oxygen, is a poisonous gas with a distinct, sharp odor. It is thermodynamically unstable toward the more common dioxygen form. It is formed continuously in the upper atmosphere of the Earth by short-wave UV radiation, and also functions as a shield against UV radiation reaching the ground. Ozone has recently been found to be produced by the immune system as an antimicrobial (see below). Liquid and solid O3 ( Ozone ) have a deeper blue color than ordinary oxygen, and they are unstable and explosive. APPLICATIONS Uptake of oxygen from the air is the essential purpose of Respiration , so oxygen supplementation has found use in Medicine (as Oxygen Therapy ). People who climb Mountain s or fly in non-pressurized Aeroplane s sometimes have supplemental oxygen supplies; the reason is that increasing the proportion of oxygen in the breathing gas at low pressure acts to augment the inspired oxygen Partial Pressure nearer to that found at sea-level. patient's house. The model shown is the DeVILBISS LT 4000.]] A notable application of oxygen as a very low-pressure breathing gas, is in modern Spacesuit s, where use of nearly pure oxygen at a total ambient pressure of about one third normal, results in normal blood Partial Pressures of oxygen. This trade-off of breathing gas content and needed pressure is important for space applications, because the issue of flexible spacesuits working at Earth sea-level pressures remains a technological challenge of aerospace technology. Oxygen is used in Welding (such as the Oxyacetylene torch), and in the industrial production of Steel and Methanol . Also, liquid oxygen finds use as a classic oxidizer in Rocket propulsion. Oxygen presents two spectrophotometric Absorption Band s 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, as a supposed mild euphoric, has a history of recreational use (see Oxygen Bar ). However, the reality of a pharmacological effect is doubtful, a metabolic boost being the most plausible explanation. Controlled tests of high oxygen mixtures in diving (see Nitrox ) and other activities, even at higher than normal pressures, demonstrated no particular effects on humans other than promotion of an increased tolerance to aerobic exercise. In the 19th century, oxygen was often mixed with Nitrous Oxide to temper its Analgesic effect. A stable 50% gaseous mixture ( Entonox ) is commonly used in medicine today as an analgesic. However, the common basic anaesthetic mixture is 30% oxygen with 70% nitrous oxide; the pain-suppressing effects, obviously, are due to the Nitrous Oxide and not to oxygen. HISTORY Oxygen was first described by Michał Sędziwój , a Polish Alchemist and Philosopher in the late 16th century. Sędziwój thought of the gas given off by warm Niter (saltpeter) as "the elixir of life". Oxygen was more quantitatively discovered by the Swedish pharmacist Carl Wilhelm Scheele some time before 1773, but the discovery was not published until after the independent discovery by Joseph Priestley on August 1 , 1774 , who called the gas ''dephlogisticated air'' (see Phlogiston Theory ). Priestley published discoveries in 1775 and Scheele in 1777 ; consequently Priestley is usually given the credit. Both Scheele and Priestley produced oxygen by heating Mercuric Oxide . Scheele called the gas 'fire air' because it was the only known supporter of combustion. It was later called 'vital air' because it was and is vital for the existence of animal life. The gas was named by Antoine Laurent Lavoisier , after Priestley's publication in 1775, from Greek roots meaning " Acid -former". As noted, the name reflects the then-common incorrect belief that all acids contain oxygen. This is also the origin of the Japanese name of oxygen "sanso" (san=acid, so=element). Oxygen was first time Condensed in 1883 by professors of Jagiellonian University - Zygmunt Wróblewski (Polish Chemist ) Karol Olszewski (Polish Physicist and chemist). BIOLOGICAL ROLE and |
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