It is a member of the chalcogen group in the periodic tablea highly reactive nonmetaland an oxidizing agent that readily forms oxides with most elements as well as with other compounds. After hydrogen and heliumoxygen is the third- most abundant element in the universe by mass. At standard temperature and pressuretwo atoms of the element bind to form dioxygena colorless and odorless diatomic gas with the formula O 2.
Diatomic oxygen gas constitutes Oxygen makes up almost half of the Earth's crust in the form of oxides. Dioxygen provides the energy released in combustion  and aerobic cellular respiration and many major classes of organic molecules in living organisms contain oxygen atoms, such as proteinsnucleic acidscarbohydratesand fatsas do the major constituent inorganic compounds of animal shells, teeth, and bone.
Most of the mass of living organisms is oxygen as a component of waterthe major constituent of lifeforms. Oxygen is continuously replenished in Earth's atmosphere by photosynthesiswhich uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too chemically reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms.
Another form allotrope of oxygen, ozone O 3strongly absorbs ultraviolet UVB radiation and the high-altitude ozone layer helps protect the biosphere from ultraviolet radiation. However, ozone present at the surface is a byproduct of smog and thus a pollutant. Oxygen was isolated by Michael Sendivogius beforebut it is commonly believed that the element was discovered independently by Carl Wilhelm Scheelein Uppsalain or earlier, and Joseph Priestley in Wiltshirein Priority is often given for Priestley because his work was published first.
Priestley, however, called oxygen "dephlogisticated air", and did not recognize it as a chemical element. The name oxygen was coined in by Antoine Lavoisierwho first recognized oxygen as a chemical element and correctly characterized the role it plays in combustion. Common uses of oxygen include production of steelplastics and textilesbrazing, welding and cutting of steels and other metalsrocket propellantoxygen therapyand life support systems in aircraftsubmarinesspaceflight and diving.
In his work PneumaticaPhilo 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.
Many centuries later Leonardo da Vinci built on Philo's work by observing that a portion of air is consumed during combustion and respiration. English chemist John Mayow — refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Robert HookeOle BorchMikhail Lomonosovand Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element.
Established in by the German alchemist J. Becherand modified by the chemist Georg Ernst Stahl by phlogiston theory stated that all combustible materials were made of two parts. 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, or calx.
Highly combustible materials that leave little residuesuch as wood or coal, were thought to be made mostly of phlogiston; non-combustible substances that corrode, such as iron, contained very little.
Air did not play a role in phlogiston theory, nor were any initial quantitative experiments conducted to test the idea; instead, it was based on observations of what happens when something burns, that most common objects appear to become lighter and seem to lose something in the process.
In Bugaj's view, the isolation of oxygen and the proper association of the substance to that part of air which is required for life, lends sufficient weight to the discovery of oxygen by Sendivogius. It is also commonly claimed that oxygen was first discovered by Swedish pharmacist Carl Wilhelm Scheele.There are several known allotropes of oxygen.
The most familiar is molecular oxygen O 2present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone O 3. Others are:. Atomic oxygen, denoted O 3 P or O 3P is very reactive, as the single atoms of oxygen tend to quickly bond with nearby molecules.
The common allotrope of elemental oxygen on Earth, O 2is generally known as oxygen, but may be called dioxygendiatomic oxygenmolecular oxygenor oxygen gas to distinguish it from the element itself and from the triatomic allotrope ozoneO 3.
Aerobic organisms release the chemical energy stored in the weak sigma bond of atmospheric dioxygen, the terminal oxidant in cellular respiration. The first excited state, singlet oxygen1 O 2, has no unpaired electrons and is metastable.
Liquid oxygen is pale blue in colour, and is quite markedly paramagnetic due to the unpaired electrons; liquid oxygen contained in a flask suspended by a string is attracted to a magnet. Singlet oxygen is the common name used for the two metastable states of molecular oxygen O 2 with higher energy than the ground state triplet oxygen.
Because of the differences in their electron shells, singlet oxygen has different chemical and physical properties than triplet oxygen, including absorbing and emitting light at different wavelengths.
It can be generated in a photosensitized process by energy transfer from dye molecules such as rose bengalmethylene blue or porphyrinsor by chemical processes such as spontaneous decomposition of hydrogen trioxide in water or the reaction of hydrogen peroxide with hypochlorite. Triatomic oxygen ozone, O 3is a very reactive allotrope of oxygen that is destructive to materials like rubber and fabrics and is also damaging to lung tissue. Ozone is thermodynamically unstable toward the more common dioxygen form, and is formed by reaction of O 2 with atomic oxygen produced by splitting of O 2 by UV radiation in the upper atmosphere.
Ozone is a pale blue gas condensable to a dark blue liquid. It is formed whenever air is subjected to an electrical discharge, and has the characteristic pungent odour of new-mown hay or subways — the so-called 'electrical odour'.
Tetraoxygen had been suspected to exist since the early s, when it was known as oxozone. It was identified in by a team led by Fulvio Cacace at the University of Rome. Cacace's team suggested that O 4 probably consists of two dumbbell-like O 2 molecules loosely held together by induced dipole dispersion forces.
There are six known distinct phases of solid oxygen. One of them is a dark-red O 8 cluster. At very low temperatures, this phase also becomes superconducting. Nascent oxygen O. Trioxygen Ozone O 3. Tetraoxygen O 4. Octaoxygen O 8. From Wikipedia, the free encyclopedia. Redirected from Atomic oxygen. Others are: Atomic oxygen O 1a free radical. Tetraoxygen O 4another metastable form. Solid oxygenexisting in six variously colored phases, of which one is O 8 and another one metallic. Main article: Oxygen.Choose another category:.
NASA research into the damage to satellites caused by atomic oxygen in low Earth orbit has led to a new way to restore damaged artwork. Atomic oxygen is an elemental form of oxygen that does not exist in Earth's atmosphere. In space, however, it is common in the area where satellites orbit Earth. There, it reacts with other materials very easily and exposes satellites and spacecraft to damaging corrosion.
Researchers at NASA's Glenn Research Center study these damaging effects in order to find materials and methods to extend the lifetime of communication satellites, the Space Shuttles and the International Space Station. Image right: The left photograph was taken after the Cleveland Museum of Art staff used acetone and methylene chloride to clean and restore the painting. The right half was taken after Glenn researchers used the atomic oxygen technique to clean the painting.
Credit: NASA While developing methods to prevent damage from atomic oxygen, researchers discovered that atomic oxygen could remove layers of soot or other organic carbon-based materials from a surface. Because atomic oxygen will not react with inorganic oxides, such as most paint pigments, it could be used to restore paintings damaged by soot. For paintings containing organic pigments which could be damaged by the atomic oxygenthe exposure could be carefully timed so that the removal would stop just short of the paint pigment.
Image right: A party-goer's lipstick smudge was finally removed from the Andy Warhol's "Bathtub" painting. Credit: NASA It has been estimated that, worldwide, an average of one collection or gallery suffers fire damage every day, and paintings damaged by charring are very resistant to traditional cleaning techniques. Current processes used to restore artwork generally use chemical solvents to remove dirt, varnish and thin layers of soot.
With damage from heavy deposits of soot, or even charring or graffiti, these techniques are not effective. The Electro-Physics Branch had facilities simulating the low-Earth-orbit environment which produce atomic oxygen that could potentially be used to restore artwork. The first tests were done on two religious paintings damaged by an arson fire at St.
Alban's Church in Cleveland Heights, Ohio. Both paintings were found to be unsalvageable by conventional art restoration wet chemistry techniques and were provided to NASA to test its atomic oxygen cleaning process. The technique not only removed the soot, but it cleaned the paintings so effectively that colors that had been faded by time were brighter, and more detail could be seen than before the fire. The success encouraged the art community to risk more important works of art to test the technique further.
Inthe atomic oxygen restoration system had its first big success. The Andy Warhol painting "Bathtub," estimated to be worth several hundred thousand dollars, had been kissed by a vandal during a party at the museum. Until they heard about Glenn's atomic oxygen restoration system, conservators had been resigned to keeping the painting in permanent storage.
Image right: Interaction of the Space Shuttle with the upper atmosphere creates a corona seen at night due, in part, to atomic oxygen. The left photograph is during the day, and the right photograph is at night. Credit: NASA Glenn researchers built a portable version of the atomic oxygen device and transported it to the museum.
Preliminary tests were done outside of the viewing area; then the device was used successfully to remove the lipstick smudge. In addition to the St. Alban and Andy Warhol paintings, a fire-damaged Roy Lichtenstein ink drawing on paper has been cleaned along with two smoke-damaged paintings from St.
Stanislaus Church Cleveland. In the upper reaches of the atmosphere, about to miles above the Earth, atomic oxygen is created by exposure to intense solar ultraviolet light.Related to Atomic oxygen: DioxygenDiatomic Oxygen. Symbol O A nonmetallic element constituting 21 percent of the atmosphere by volume that occurs as a diatomic gas, O 2and in many compounds such as water and silica, and in iron ore. It combines with most elements, is essential for plant and animal respiration, and is required for nearly all combustion.
Ozone, O 3is an allotrope of this element. Atomic number 8; atomic weight See Periodic Table. Word History: One of the most important substances on earth is misnamed. Oxygen had been discovered a few years before by Joseph Priestley inand he had called the gas dephlogisticated air. The same publication also introduced the French words that were soon adopted into English as hydrogen and sodium chloride common saltamong other terms commonly used in chemistry.
Although this is not the case, the name oxygen has persisted for the element. All rights reserved. It is essential for aerobic respiration and almost all combustion and is widely used in industry.
Symbol: O; atomic no: 8; atomic wt: Symbol: O; at. Copyright, by Random House, Inc. Symbol O A nonmetallic element that exists in its free form as a colorless, odorless gas and makes up about 21 percent of the Earth's atmosphere.
It is the most abundant element in the Earth's crust and occurs in many compounds, including water, carbon dioxide, and iron ore.
Oxygen combines with most elements, is required for combustion, and is essential for life in most organisms. Atomic number 8. He used Greek words for the coinage: oxy- means "sharp," and -gen means "producing. Lavoisier also coined the name of the element hydrogen, the "water-producing" element, in Soon after, inanother French chemist, J.
Chaptal, introduced the word nitrogenthe "niter-producing" element, referring to its discovery from an analysis of nitric acid. Switch to new thesaurus. H2Owater - binary compound that occurs at room temperature as a clear colorless odorless tasteless liquid; freezes into ice below 0 degrees centigrade and boils above degrees centigrade; widely used as a solvent.
Based on WordNet 3. He died from lack of oxygen. Mentioned in? References in periodicals archive? Atomic oxygen wall recombination coefficient [k. Meanwhile, [Na. Synthesis and growth mechanism of silver nanowires through different mediated agents Cu[Cl.
She has teamed with retired Goddard scientist Fred Herrero, who is pursuing the research in an emeritus capacity, to develop a miniaturized, low-mass, low-power, graphene-based detector that could measure the amount of atomic oxygen in the upper atmosphere. Graphene-based sensors to detect trace elements in Earth's upper atmosphere.
Distribution of oxygen in single crystals of silicon and its influence on life time of non-equilibrium charge carriers. The 27 papers examine fundamental properties and the response of materials in such extremes as static and dynamic high pressure, high strain and high strain rates, high radiation and electromagnetic fields, high and low temperatures, corrosive environments, and atomic oxygen.
Among the behavior and responses are crack branching, structural transition to super-protonic phase under high pressure, tensile and optical properties of the Hubble telescope's insulation, and nanostructure evolution. Materials in extreme environments; proceedings. Atomic oxygen AOa natural species in the earth's atmosphere, is formed when ultraviolet UV radiation photo-dissociates oxygen molecules.
Space flight experiment to measure polymer erosion and silicone contamination on spacecraft.The effects of atomic oxygen monatomic oxygen bombardment were originally highlighted with the early shuttle flights, by a visible effect on exposed polymer surfaces such as Kapton, where changes in characteristics due to atomic oxygen were found to cause undesirable temperature excursions in low Earth orbit and shorten the useful lifetime of many spacecraft components.
It has also been proposed that atmospheric atomic oxygen plays a role in the production of a visible shuttle glow upon re-entry into Earth's atmosphere. Post-flight analysis of painted surfaces on the shuttle were also noted to have been returned with a brighter surface than prior to launch.
Atomic oxygen bombardment contributes significantly to surface degradation, erosion, and contamination of materials with which it collides due to its high speed of 1. At this energy, atomic oxygen initiates a number of chemical and physical reactions with the materials and penetrate surfaces, substituting oxygen to form oxide compounds, more stable than those originally present.
The effects of atomic oxygen bombardment on a polymer film produces a heavily etched and eroded surface. Polymer films that have been coated with thin metallic layers have suffered atomic oxygen attack through pre-existing pinholes in the metal film, this leads to underlying cavities which eventually produces complete loss of the polymer, leaving a free-standing metal film. As the orbit of the LDEF was inclined to the equator The angle of each experiment surface relative to the ram direction was used to determine the atomic oxygen fluence by the fixed structural geometry of the vehicle and its constant flight attitude in orbit.
The extent to which on-board materials were exposed to atomic oxygen, the total atomic oxygen fluence, is of primary interest.
The altitude of the flight, orientation of the surfaces, and the extent of solar activity determine the amount of atomic oxygen exposure. Atomic oxygen flux was not constant during the orbital lifetime of the LDEF as decreasing solar activity caused atomic oxygen flux to decrease during the first three years of the flight.
Following this, the combination of increasing solar activity and decreasing altitude caused the atomic oxygen flux to increase rapidly. The flux during the latter months of the mission was almost two orders of magnitude greater than the flux encountered early in the mission. Figure 10 shows the accumulated atomic oxygen fluence expressed as a percentage of the total fluence exposed for the mission.
This highlights the combined effect on atomic oxygen fluence caused by the varying solar activity and the loss in altitude. Figure 11 shows the expected atomic oxygen fluence profile for a five year polar orbit at an altitude of km with values ranging from approximately 8x10 20 to 1x10 20this compares to a range of 1x10 20 to 5x10 21 experienced by the LDEF leading edge tray B8.
It should be noted that the optical elements on the LDEF experiment were under direct exposure to the flux of atomic oxygen, whilst in HIRDLS the filters are internal to instrument, providing far greater protection for survival.★ How to Get to Mars. Very Cool! HD
Atomic oxygen The effects of atomic oxygen monatomic oxygen bombardment were originally highlighted with the early shuttle flights, by a visible effect on exposed polymer surfaces such as Kapton, where changes in characteristics due to atomic oxygen were found to cause undesirable temperature excursions in low Earth orbit and shorten the useful lifetime of many spacecraft components. Figure 10, Cumulative Atomic Oxygen fluence as a percentage of total exposure. Things to do now Find out more about our products and services Find out more about our research interests Contact us Email: irfilters reading.
A-Z lists Search.Since the standard unit of atomic mass has been one-twelfth the mass of an atom of the isotope carbon The atomic weight of helium is 4.
Atomic weight is measured in atomic mass units amualso called daltons. See below for a list of chemical elements and their atomic weights.
The concept of atomic weight is fundamental to chemistrybecause most chemical reactions take place in accordance with simple numerical relationships among atoms. Since it is almost always impossible to count the atoms involved directly, chemists measure reactants and products by weighing and reach their conclusions through calculations involving atomic weights.
The quest to determine the atomic weights of elements occupied the greatest chemists of the 19th and early 20th centuries. Their careful experimental work became the key to chemical science and technology.
Reliable values for atomic weights serve an important purpose in a quite different way when chemical commodities are bought and sold on the basis of the content of one or more specified constituents. The ores of expensive metals such as chromium or tantalum and the industrial chemical soda ash are examples. The content of the specified constituent must be determined by quantitative analysis. The computed worth of the material depends on the atomic weights used in the calculations.
The original standard of atomic weight, established in the 19th century, was hydrogenwith a value of 1. From about untiloxygen was used as the reference standard, with an assigned value of In it was discovered that natural oxygen contains small amounts of two isotopes slightly heavier than the most abundant one and that the number 16 represented a weighted average of the three isotopic forms of oxygen as they occur in nature. This situation was considered undesirable for several reasons, and, since it is possible to determine the relative masses of the atoms of individual isotopic species, a second scale was soon established with 16 as the value of the principal isotope of oxygen rather than the value of the natural mixture.
This second scale, preferred by physicists, came to be known as the physical scale, and the earlier scale continued in use as the chemical scale, favoured by chemists, who generally worked with the natural isotopic mixtures rather than the pure isotopes. Although the two scales differed only slightly, the ratio between them could not be fixed exactly, because of the slight variations in the isotopic composition of natural oxygen from different sources.
It was also considered undesirable to have two different but closely related scales dealing with the same quantities. For both of these reasons, chemists and physicists established a new scale in This scale, based on carbon, required only minimal changes in the values that had been used for chemical atomic weights.
Since samples of elements found in nature contain mixtures of isotopes of different atomic weights, the International Union of Pure and Applied Chemistry IUPAC began publishing atomic weights with uncertainties.
The first element to receive an uncertainty in its atomic weight was sulfur in By18 elements had associated uncertainties, and inIUPAC began publishing ranges for the atomic weight of some elements. For example, the atomic weight of carbon is given as [ The table provides a list of chemical elements and their atomic weights. Atomic weight.
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Allotropes of oxygen
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Such a situation can occur only if the atoms have different numbers of neutrons in their nuclei. Such groups of atoms—with the same atomic number but with different relative weights—are called isotopes.The key difference between atomic oxygen and molecular oxygen is that the atomic oxygen is highly reactive and does not exist in the atmosphere as it is whereas the molecular oxygen is less reactive and exists in the atmosphere as it is.
Moreover, atomic oxygen is a free radical having the symbol O 3P while the molecular oxygen is a diatomic oxygen having the symbol O 2. Oxygen is a chemical element having the atomic number 8. But when we refer to oxygen in common use, we are talking about molecular oxygen that we breathe.
It has two oxygen atoms bonded to each other via covalent bond. Atomic oxygen has one oxygen atom. Therefore, it cannot exist as an individual chemical species because of its high reactivity. Overview and Key Difference 2. What is Atomic Oxygen 3. What is Molecular Oxygen 4. Atomic oxygen is a very reactive chemical species having the symbol O 3P.
It is a free radical. This means atomic oxygen has an unpaired electron that makes this atom highly reactive. Therefore, this atom does not exist naturally for even a short period; it tends to react with other chemical elements or compounds to become stable by pairing its unpaired electron.
This chemical species plays a major role in corrosion in space. Corrosion in space is the corrosion of materials occurring in outer space. Molecular oxygen is diatomic oxygen having the symbol O 2.
It contains two oxygen atoms bonded to each other via covalent bonding. There is a double bond between these two atoms. Since the two oxygen atoms have eight electrons around them, the oxygen molecule is less reactive. Therefore, this chemical species exist in the atmosphere itself. This amount of oxygen is essential for all the organisms for their respiration. It does not exist naturally for even a short period, but in outer space, it is the predominant form of oxygen.