There are six known distinct phases of solid oxygen. One of them is a dark-red cluster. When oxygen is subjected to a pressure of 96 GPa, it becomes metallic, in a similar manner to hydrogen, and becomes more similar to the heavier chalcogens, such as tellurium and polonium, both of which show significant metallic character. At very low temperatures, this phase also becomes superconducting.
Phases of solid oxygen
Allotropes of oxygen
Allotropes of oxygen | Phases of solid oxygen
No it is not toxic It can be toxic at elevated partial pressures, leading to convulsions and other health problems. It  can be toxic at elevated partial pressures, leading to convulsions and other health problems. Yes, at elevated partial pressures.
oxygen (o2) is formed in photosynthesis as a direct result of
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Light-driven splitting of water during oxygenic photosynthesis
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how does lavoisier contribute?
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He conducted the first adequate quantitative experiments on oxidation and gave the first correct explanation of how combustion works
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what are its isotopes?
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They are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number
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what are its allotropes?
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Sorry. I cannot find the answer based on the context.
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how is it stored?
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Sorry. I cannot find the answer based on the context.
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is it toxic?
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There are six known distinct phases of solid oxygen. One of them is a dark-red cluster. When oxygen is subjected to a pressure of 96 GPa, it becomes metallic, in a similar manner to hydrogen, and becomes more similar to the heavier chalcogens, such as tellurium and polonium, both of which show significant metallic character. At very low temperatures, this phase also becomes superconducting.
Allotropes of oxygen | Phases of solid oxygen
Oxygen is generally nontoxic, but oxygen toxicity has been reported when it is used in high concentrations. In both elemental gaseous form and as a component of water, it is vital to almost all life on earth. Despite this, liquid oxygen is highly dangerous. Even gaseous oxygen is dangerous in excess. For instance, sports divers have occasionally drowned from convulsions caused by breathing pure oxygen at a depth of more than underwater. Oxygen is also toxic to some bacteria. Ozone, an allotrope of oxygen, is toxic to most life. It can cause lesions in the respiratory tract. Sulfur is generally nontoxic and is even a vital nutrient for humans.
Chalcogen | Toxicity
It was proven in 2006 that this phase, created by pressurizing to 20 GPa, is in fact a rhombohedral cluster. This cluster has the potential to be a much more powerful oxidizer than either or and may therefore be used in rocket fuel. A metallic phase was discovered in 1990 when solid oxygen is subjected to a pressure of above 96 GPa and it was shown in 1998 that at very low temperatures, this phase becomes superconducting.
Oxygen | Allotropes
General The following external site is a compendium of resources: Specialised
Oxygen toxicity | External links
Oxygen toxicity is a condition resulting from the harmful effects of breathing molecular oxygen () at increased partial pressures. Severe cases can result in cell damage and death, with effects most often seen in the central nervous system, lungs, and eyes. Historically, the central nervous system condition was called the "Paul Bert effect", and the pulmonary condition the "Lorrain Smith effect", after the researchers who pioneered the discoveries and descriptions in the late 19th century. Oxygen toxicity is a concern for underwater divers, those on high concentrations of supplemental oxygen (particularly premature babies), and those undergoing hyperbaric oxygen therapy. The result of breathing increased partial pressures of oxygen is hyperoxia, an excess of oxygen in body tissues.
Oxygen toxicity | Introduction
Oxygen gas () can be toxic at elevated partial pressures, leading to convulsions and other health problems. Oxygen toxicity usually begins to occur at partial pressures more than 50 kilopascals (kPa), equal to about 50% oxygen composition at standard pressure or 2.5 times the normal sea-level partial pressure of about 21 kPa. This is not a problem except for patients on mechanical ventilators, since gas supplied through oxygen masks in medical applications is typically composed of only 30%–50% by volume (about 30 kPa at standard pressure). At one time, premature babies were placed in incubators containing -rich air, but this practice was discontinued after some babies were blinded by the oxygen content being too high.
Oxygen | Toxicity
The NFPA 704 standard rates compressed oxygen gas as nonhazardous to health, nonflammable and nonreactive, but an oxidizer. Refrigerated liquid oxygen (LOX) is given a health hazard rating of 3 (for increased risk of hyperoxia from condensed vapors, and for hazards common to cryogenic liquids such as frostbite), and all other ratings are the same as the compressed gas form.
Oxygen | Safety and precautions
Triatomic oxygen (ozone, O), is a very reactive allotrope of oxygen that is destructive to materials like rubber and fabrics and is also damaging to lung tissue. Traces of it can be detected as a sharp, chlorine-like smell, coming from electric motors, laser printers, and photocopiers. It was named "ozon" in 1840 by Christian Friedrich Schönbein, from ancient Greek ὄζειν (ozein: "to smell") plus the suffix "-on" (in English "-one") commonly used at the time to designate a derived compound. Ozone is thermodynamically unstable toward the more common dioxygen form, and is formed by reaction of O with atomic oxygen produced by splitting of O by UV radiation in the upper atmosphere.
Allotropes of oxygen | Ozone
The doublet state requires an odd number of electrons, and so cannot occur in dioxygen without gaining or losing electrons, such as in the superoxide ion () or the dioxygenyl ion (). The ground state of has a bond length of 121 pm and a bond energy of 498 kJ/mol. It is a colourless gas with a boiling point of . It can be condensed from air by cooling with liquid nitrogen, which has a boiling point of . 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.
Allotropes of oxygen | Dioxygen
Tetraoxygen had been suspected to exist since the early 1900s, when it was known as oxozone. It was identified in 2001 by a team led by Fulvio Cacace at the University of Rome. The molecule was thought to be in one of the phases of solid oxygen later identified as . Cacace's team suggested that probably consists of two dumbbell-like molecules loosely held together by induced dipole dispersion forces.
Allotropes of oxygen | Tetraoxygen
Cell damage and cell death then result.
Oxygen toxicity | Mechanism
Nitrogen itself is relatively non-toxic, but in high concentrations it can displace oxygen, creating a suffocation hazard. Liquid nitrogen (−195.8 °C) presents a significant risk of frostbite or cold burn if mishandled. Proper protective clothing, such as long sleeves and gloves, should always be worn when handling these products. Liquid nitrogen is stored in compressed cylinders, and therefore presents all the hazards attendant to materials under pressure and should be handled accordingly.
Theatrical smoke and fog | Liquid nitrogen
The biochemical basis for the toxicity of oxygen is the partial reduction of oxygen by one or two electrons to form reactive oxygen species, which are natural by-products of the normal metabolism of oxygen and have important roles in cell signalling. One species produced by the body, the superoxide anion (), is possibly involved in iron acquisition. Higher than normal concentrations of oxygen lead to increased levels of reactive oxygen species. Oxygen is necessary for cell metabolism, and the blood supplies it to all parts of the body. When oxygen is breathed at high partial pressures, a hyperoxic condition will rapidly spread, with the most vascularised tissues being most vulnerable.
Oxygen toxicity | Mechanism
The effects of oxygen toxicity may be classified by the organs affected, producing three principal forms: Central nervous system oxygen toxicity can cause seizures, brief periods of rigidity followed by convulsions and unconsciousness, and is of concern to divers who encounter greater than atmospheric pressures. Pulmonary oxygen toxicity results in damage to the lungs, causing pain and difficulty in breathing. Oxidative damage to the eye may lead to myopia or partial detachment of the retina. Pulmonary and ocular damage are most likely to occur when supplemental oxygen is administered as part of a treatment, particularly to newborn infants, but are also a concern during hyperbaric oxygen therapy.
Oxygen toxicity | Classification
They called having an oxygen toxicity attack "getting a Pete".
Oxygen toxicity | History
Breathing 100% oxygen also eventually leads to collapse of the alveoli (atelectasis), while—at the same partial pressure of oxygen—the presence of significant partial pressures of inert gases, typically nitrogen, will prevent this effect. Preterm newborns are known to be at higher risk for bronchopulmonary dysplasia with extended exposure to high concentrations of oxygen. Other groups at higher risk for oxygen toxicity are patients on mechanical ventilation with exposure to levels of oxygen greater than 50%, and patients exposed to chemicals that increase risk for oxygen toxicity such the chemotherapeutic agent bleomycin. Therefore, current guidelines for patients on mechanical ventilation in intensive care recommends keeping oxygen concentration less than 60%.
Oxygen toxicity | Lung toxicity
There are several known allotropes of oxygen. The most familiar is molecular oxygen (O), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O). Others are:
Allotropes of oxygen | Introduction
In low-pressure environments oxygen toxicity may be avoided since the toxicity is caused by high partial pressure of oxygen, not merely by high oxygen fraction. This is illustrated by modern pure oxygen use in spacesuits, which must operate at low pressure (also historically, very high percentage oxygen and lower than normal atmospheric pressure was used in early spacecraft, for example, the Gemini and Apollo spacecraft). In such applications as extra-vehicular activity, high-fraction oxygen is non-toxic, even at breathing mixture fractions approaching 100%, because the oxygen partial pressure is not allowed to chronically exceed .
Oxygen toxicity | Hypobaric setting
Oxygen difluoride is considered an unsafe gas due to its oxidizing properties. Hydrofluoric acid produced by the hydrolysis of OF2 with water is highly corrosive and toxic, capable of causing necrosis, leaching calcium from the bones and cardiovascular damage, among a host of other insidious effects.
Oxygen difluoride | Safety
Oxygen toxicity is caused by exposure to oxygen at partial pressures greater than those to which the body is normally exposed. This occurs in three principal settings: underwater diving, hyperbaric oxygen therapy, and the provision of supplemental oxygen, particularly to premature infants. In each case, the risk factors are markedly different.
Oxygen toxicity | Causes
At partial pressures of oxygen of —100% oxygen at 2 to 3 times atmospheric pressure—these symptoms may begin as early as 3 hours after exposure to oxygen. Experiments on rats breathing oxygen at pressures between suggest that pulmonary manifestations of oxygen toxicity may not be the same for normobaric conditions as they are for hyperbaric conditions. Evidence of decline in lung function as measured by pulmonary function testing can occur as quickly as 24 hours of continuous exposure to 100% oxygen, with evidence of diffuse alveolar damage and the onset of acute respiratory distress syndrome usually occurring after 48 hours on 100% oxygen.
Oxygen toxicity | Lung toxicity
Oxygen's most common allotrope is diatomic oxygen, or O, a reactive paramagnetic molecule that is ubiquitous to aerobic organisms and has a blue color in its liquid state. Another allotrope is O, or ozone, which is three oxygen atoms bonded together in a bent formation. There is also an allotrope called tetraoxygen, or O, and six allotropes of solid oxygen including "red oxygen", which has the formula O. Sulfur has over 20 known allotropes, which is more than any other element except carbon. The most common allotropes are in the form of eight-atom rings, but other molecular allotropes that contain as few as two atoms or as many as 20 are known.
Chalcogen | Allotropes
Acute, or central nervous system oxygen toxicity is a time variable response to the partial pressure exposure history of the diver and is both complex and not fully understood. Central nervous system oxygen toxicity manifests as symptoms such as visual changes (especially tunnel vision), ringing in the ears (tinnitus), nausea, twitching (especially of the face), behavioural changes (irritability, anxiety, confusion), and dizziness. This may be followed by a tonic–clonic seizure consisting of two phases: intense muscle contraction occurs for several seconds (tonic phase); followed by rapid spasms of alternate muscle relaxation and contraction producing convulsive jerking (clonic phase). The seizure ends with a period of unconsciousness (the postictal state).
Maximum operating depth | Safe limit of partial pressure of oxygen
To balance the risks of hypoxia and retinopathy of prematurity, modern protocols now require monitoring of blood oxygen levels in premature infants receiving oxygen.
Oxygen toxicity | Normobaric setting
Luxfer cylinders specify oxygen cleaning for all mixtures exceeding 23.5% oxygen.
Nitrox | Fire and toxic cylinder contamination from oxygen reactions
These compounds form by oxidation of alkali metals with larger ionic radii (K, Rb, Cs). For example, potassium superoxide () is an orange-yellow solid formed when potassium reacts with oxygen. Hydrogen peroxide () can be produced by passing a volume of 96% to 98% hydrogen and 2 to 4% oxygen through an electric discharge. A more commercially-viable method is to allow autoxidation of an organic intermediate, 2-ethylanthrahydroquinone dissolved in an organic solvent, to oxidize to and 2-ethylanthraquinone. The 2-ethylanthraquinone is then reduced and recycled back into the process.
Compounds of oxygen | Other inorganic compounds
Diving below on air would expose a diver to increasing danger of oxygen toxicity as the partial pressure of oxygen exceeds , so a gas mixture must be used which contains less than 21% oxygen (a hypoxic mixture). Increasing the proportion of nitrogen is not viable, since it would produce a strongly narcotic mixture. However, helium is not narcotic, and a usable mixture may be blended either by completely replacing nitrogen with helium (the resulting mix is called heliox), or by replacing part of the nitrogen with helium, producing a trimix.
Oxygen toxicity | Underwater
Reductions in pressure and exposure will be made progressively, and medications such as bronchodilators and pulmonary surfactants may be used.
Oxygen toxicity | Management
In this phase it exhibits a dark-red color, very strong infrared absorption, and a magnetic collapse. It is also stable over a very large pressure domain and has been the subject of numerous X-ray diffraction, spectroscopic and theoretical studies. It has been shown to have a monoclinic C2/m symmetry and its infrared absorption behaviour was attributed to the association of oxygen molecules into larger units.
Solid oxygen | Red oxygen
The toxic metabolites may bind to vital intracellular macromolecules and may generate reactive oxygens by redox cycling if quinone is formed. This could also lead to a depletion of protective glutathione which is responsible for the detoxification of reactive oxygens.
Benoxaprofen | Toxicity
Manufacturers recommend that carbon tetraiodide be stored near . As a ready source of iodine, it is an irritant. Its LD is 178 mg.kg. In general, perhalogenated organic compounds should be considered toxic, with the narrow exception of small perfluoroalkanes (essentially inert due to the strength of the C-F bond).
Carbon tetraiodide | Safety considerations
Breathing pure in space applications, such as in some modern space suits, or in early spacecraft such as Apollo, causes no damage due to the low total pressures used. In the case of spacesuits, the partial pressure in the breathing gas is, in general, about 30 kPa (1.4 times normal), and the resulting partial pressure in the astronaut's arterial blood is only marginally more than normal sea-level partial pressure.
Oxygen | Toxicity
OF precipitates as a brown solid upon the UV irradiation of a mixture of liquid O and F at -196 °C. It also only appears to be stable below -160 °C. The general method of preparation of many oxygen fluorides is a gas-phase electric discharge in cold containers including OF. It is typically an orange-yellow solid which rapidly decomposes to O and F close to its normal boiling point of about 216 K. OF reacts violently with red phosphorus, even at -196 °C. Explosions can also occur if Freon-13 is used to moderate the reaction.
Oxygen fluoride | Dioxygen difluoride (OF)
High concentrations of oxygen can cause oxygen toxicity such as lung damage or result in respiratory failure in those who are predisposed. It can also dry out the nose and increase the risk of fires in those who smoke. The target oxygen saturation recommended depends on the condition being treated. In most conditions a saturation of 94-98% is recommended, while in those at risk of carbon dioxide retention saturations of 88-92% are preferred, and in those with carbon monoxide toxicity or cardiac arrest the saturation should be as high as possible. The use of oxygen in medicine become common around 1917.
Breathing gas | Oxygen therapy
Likewise, divers who undergo treatment of decompression sickness are at increased risk of oxygen toxicity as treatment entails exposure to long periods of oxygen breathing under hyperbaric conditions, in addition to any oxygen exposure during the dive.
Oxygen toxicity | Lung toxicity
The common allotrope of elemental oxygen on Earth is called dioxygen, , the major part of the Earth's atmospheric oxygen (see Occurrence). O has a bond length of 121 pm and a bond energy of 498 kJ/mol, which is smaller than the energy of other double bonds or pairs of single bonds in the biosphere and responsible for the exothermic reaction of O with any organic molecule. Due to its energy content, O is used by complex forms of life, such as animals, in cellular respiration. Other aspects of are covered in the remainder of this article. Trioxygen () is usually known as ozone and is a very reactive allotrope of oxygen that is damaging to lung tissue.
Oxygen | Allotropes
The lungs and the remainder of the respiratory tract are exposed to the highest concentration of oxygen in the human body and are therefore the first organs to show toxicity. Pulmonary toxicity occurs only with exposure to partial pressures of oxygen greater than , corresponding to an oxygen fraction of 50% at normal atmospheric pressure. The earliest signs of pulmonary toxicity begin with evidence of tracheobronchitis, or inflammation of the upper airways, after an asymptomatic period between 4 and 22 hours at greater than 95% oxygen, with some studies suggesting symptoms usually begin after approximately 14 hours at this level of oxygen.
Oxygen toxicity | Lung toxicity
The neon-burning process creates additional O. Solid samples (organic and inorganic) for O studies are usually stored in silver cups and measured with pyrolysis and mass spectrometry. Researchers need to avoid improper or prolonged storage of the samples for accurate measurements.
Oxygen-16 | Introduction
Ozone absorbs strongly in the ultraviolet and functions as a shield for the biosphere against the mutagenic and other damaging effects of solar UV radiation (see ozone layer). Ozone is formed near the Earth's surface by the photochemical disintegration of nitrogen dioxide from the exhaust of automobiles. Ground-level ozone is an air pollutant that is especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma. The immune system produces ozone as an antimicrobial (see below). Liquid and solid O have a deeper blue color than ordinary oxygen and they are unstable and explosive.
Allotropes of oxygen | Ozone
Containers must allow venting of oxygen produced by decomposition over time, otherwise they may burst.
Sodium hypochlorite | Storage hazards
Nitrogen gas is completely nontoxic, but breathing in pure nitrogen gas is deadly, because it causes nitrogen asphyxiation. The buildup of nitrogen bubbles in the blood, such as those that may occur during scuba diving, can cause a condition known as the "bends" (decompression sickness). Many nitrogen compounds such as hydrogen cyanide and nitrogen-based explosives are also highly dangerous. White phosphorus, an allotrope of phosphorus, is toxic, with 1 milligram per kilo bodyweight being a lethal dose. White phosphorus usually kills humans within a week of ingestion by attacking the liver. Breathing in phosphorus in its gaseous form can cause an industrial disease called "phossy jaw", which eats away the jawbone.
Pnictogen | Toxicity
A common preparative method involves fluorination of sodium hydroxide: OF is a colorless gas at room temperature and a yellow liquid below 128 K. Oxygen difluoride has an irritating odor and is poisonous. It reacts quantitatively with aqueous haloacids to give free halogens: It can also displace halogens from their salts. It is both an effective fluorinating agent and a strong oxidizing agent. When reacted with unsaturated nitrogen fluorides with electrical discharge, it results in the formation of nitrogen trifluoride, oxide fluorides and other oxides.
Oxygen fluoride | Oxygen difluoride (OF)
There is the possibility of asphyxiation because of laryngeal oedema and stenosis of the glottis. The lack of oxygen is then the cause of death. Otherwise the patient will die of bronchial pneumonia and lung bleeding.
T-2 mycotoxin | Toxic effects
The supplementation of oxygen can lead to oxygen toxicity, also known as oxygen toxicity syndrome, oxygen intoxication, and oxygen poisoning. There are two main types of oxygen toxicity: central nervous system toxicity (CNS), and pulmonary and ocular toxicity. Temporary exposure to high partial pressures of oxygen at greater than atmospheric pressure can lead to central nervous system toxicity (CNS). An early but serious sign of CNS oxygen toxicity is a grand-mal seizure, also known as a generalized tonic-clonic seizure. This type of seizure consists of a loss of consciousness and violent muscle contractions. Signs and symptoms of oxygen toxicity are usually prevalent, but there are no standard warning signs that a seizure is about to ensue.
Hyperoxia | Oxygen toxicity
Singlet oxygen is the common name used for the two metastable states of molecular oxygen (O) 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 bengal, methylene blue or porphyrins, or by chemical processes such as spontaneous decomposition of hydrogen trioxide in water or the reaction of hydrogen peroxide with hypochlorite.
Allotropes of oxygen | Singlet oxygen
A mild cough usually ensues, followed by greater irritation and a worse cough until breathing becomes quite painful and the cough becomes uncontrollable. If supplementation of oxygen is continued, the individual will notice tightness in the chest, difficulty breathing, shortness of breath, and if exposure is continued, fatality due to lack of oxygen.
Hyperoxia | Oxygen toxicity
Stability: Stable under ordinary conditions of use and storage. Hazardous Decomposition Products : Oxides of nitrogen and toxic metal fumes may form when heated to decomposition. Hazardous Polymerization: Will not occur. Incompatibilities: Heavy metals, phosphites, organic compounds, carbonaceous materials, strong acids, and many other substances. Conditions to Avoid: Heat, flames, ignition sources and incompatibles.
Potassium nitrate (data page) | Stability and Reactivity
In 1912, Bornstein developed cramps in his hands and legs while breathing oxygen at for 51 minutes. Smith then went on to show that intermittent exposure to a breathing gas with less oxygen permitted the lungs to recover and delayed the onset of pulmonary toxicity. Albert R. Behnke "et al." in 1935 were the first to observe visual field contraction (tunnel vision) on dives between and . During World War II, Donald and Yarbrough "et al." performed over 2,000 experiments on oxygen toxicity to support the initial use of closed circuit oxygen rebreathers. Naval divers in the early years of oxygen rebreather diving developed a mythology about a monster called "Oxygen Pete", who lurked in the bottom of the Admiralty Experimental Diving Unit "wet pot" (a water-filled hyperbaric chamber) to catch unwary divers.
Oxygen toxicity | History
A less immediately threatening form known as pulmonary oxygen toxicity occurs after exposures to lower oxygen partial pressures for much longer periods than generally encountered in scuba diving, but is a recognised problem in saturation diving.
Diving hazards | Oxygen toxicity
Oxidative damage may occur in any cell in the body but the effects on the three most susceptible organs will be the primary concern. It may also be implicated in damage to red blood cells (haemolysis), the liver, heart, endocrine glands (adrenal glands, gonads, and thyroid), or kidneys, and general damage to cells.
Oxygen toxicity | Classification
Oxygen balance (OB, or OB%) is an expression that is used to indicate the degree to which an explosive can be oxidized. If an explosive molecule contains just enough oxygen to form carbon dioxide from carbon, water from hydrogen atoms, all of its sulfur dioxide from sulfur, and all metal oxides from metals with no excess, the molecule is said to have a zero oxygen balance. The molecule is said to have a positive oxygen balance if it contains more oxygen than is needed and a negative oxygen balance if it contains less oxygen than is needed; the combustion will then be incomplete, and large amount of toxic gases like carbon monoxide will be present.
Oxygen balance | Introduction
Care should be taken when using a cold trap not to condense liquid oxygen (a light blue liquid) into the cold trap. Liquid oxygen is potentially explosive, and this is especially true if the trap has been used to trap solvent. Liquid oxygen can be condensed into a cold trap if a pump has sucked air through the trap when the trap is very cold, e.g. when cooled with liquid nitrogen. Besides oxygen, many hazardous gases emitted in reactions, e.g. sulfur dioxide, chloromethane, condense into cold traps.
Cold trap | Hazards
Studies show that, in the long term, a robust recovery from most types of oxygen toxicity is possible. Protocols for avoidance of the effects of hyperoxia exist in fields where oxygen is breathed at higher-than-normal partial pressures, including underwater diving using compressed breathing gases, hyperbaric medicine, neonatal care and human spaceflight. These protocols have resulted in the increasing rarity of seizures due to oxygen toxicity, with pulmonary and ocular damage being mainly confined to the problems of managing premature infants.
Oxygen toxicity | Introduction
The patient then remains at that pressure for a further 150 minutes, consisting of two periods of 15 minutes air/60 minutes oxygen, before the pressure is reduced to atmospheric over 30 minutes on oxygen. Vitamin E and selenium were proposed and later rejected as a potential method of protection against pulmonary oxygen toxicity. There is however some experimental evidence in rats that vitamin E and selenium aid in preventing "in vivo" lipid peroxidation and free radical damage, and therefore prevent retinal changes following repetitive hyperbaric oxygen exposures.
Oxygen toxicity | Hyperbaric setting
As the pressure of oxygen at room temperature is increased through 10 GPa (1,450,377 psi), it undergoes a dramatic phase transition to a different allotrope. Its volume decreases significantly, and it changes color from sky-blue to deep red. This ε-phase was discovered in 1979, but the structure has been unclear. Based on its infrared absorption spectrum, researchers assumed in 1999 that this phase consists of molecules in a crystal lattice. However, in 2006, it was shown by X-ray crystallography that this stable phase known as ε oxygen or red oxygen is in fact . No one predicted the structure theoretically: a rhomboid cluster consisting of four molecules.
Solid oxygen | Red oxygen
Oxygen toxicity occurs when the tissues are exposed to an excessive combination of partial pressure (PPO) and duration. In acute cases it affects the central nervous system and causes a seizure, which can result in the diver losing consciousness, spitting out their regulator and drowning. While the exact limit is not reliably predictable, and is affected by carbon dioxide levels, it is generally recognised that central nervous system oxygen toxicity is preventable if one does not exceed an oxygen partial pressure of 1.4 bar. For deep dives – generally past 180 feet (55 m), divers use "hypoxic blends" containing a lower percentage of oxygen than atmospheric air.
Diving hazards | Oxygen toxicity
The book states that this chemical is also toxic.
Ipomoea tricolor | Toxic treatments
Both roots and top parts are poisonous to mammals.
Oxypolis rigidior | Toxicity
The "false" or unphysiologic red-coloring effect in anoxic CO-poisoned tissue is related to the meat-coloring commercial use of carbon monoxide, discussed below.
Carbon monoxide | Toxicity
The common allotrope of elemental oxygen on Earth, , is generally known as oxygen, but may be called "dioxygen", "diatomic oxygen", "molecular oxygen", or "oxygen gas" to distinguish it from the element itself and from the triatomic allotrope "ozone," . As a major component (about 21% by volume) of Earth's atmosphere, elemental oxygen is most commonly encountered in the diatomic form. Aerobic organisms release the chemical energy stored in the weak sigma bond of atmospheric dioxygen, the terminal oxidant in cellular respiration. The ground state of dioxygen is known as triplet oxygen, O, because it has two unpaired electrons. The first excited state, singlet oxygen, ""O has no unpaired electrons and is metastable.
Allotropes of oxygen | Dioxygen
When heated, myclobutanil decomposes to produce corrosive and/or toxic fumes, including carbon monoxide, carbon dioxide, hydrogen chloride, hydrogen cyanide, and nitrogen oxides.
Myclobutanil | Safety
The presence of other complicating diseases also reduces the likelihood of a favourable outcome.
Oxygen toxicity | Prognosis
Many nonmetals have less stable allotropes, with either nonmetallic or metallic properties. Graphite, the standard state of carbon, has a lustrous appearance and is a fairly good electrical conductor. The diamond allotrope of carbon is clearly nonmetallic, however, being translucent and having a relatively poor electrical conductivity. Carbon is also known in several other allotropic forms, including semiconducting buckminsterfullerene (C). Nitrogen can form gaseous tetranitrogen (N), an unstable polyatomic molecule with a lifetime of about one microsecond. Oxygen is a diatomic molecule in its standard state; it also exists as ozone (O), an unstable nonmetallic allotrope with a half-life of around half an hour.
Nonmetal | Allotropes
The prevention of oxygen toxicity depends entirely on the setting. Both underwater and in space, proper precautions can eliminate the most pernicious effects. Premature infants commonly require supplemental oxygen to treat complications of preterm birth. In this case prevention of bronchopulmonary dysplasia and retinopathy of prematurity must be carried out without compromising a supply of oxygen adequate to preserve the infant's life.
Oxygen toxicity | Prevention
Neutral dihydrogen polyoxides containing up to five oxygen atoms have been produced experimentally. Hydrogen polyoxides containing up to 10 oxygen atoms have been studied theoretically, but those containing more than five oxygens are expected to be extremely unstable.
Hydrogen polyoxide | HO
The body is affected in different ways depending on the type of exposure. Central nervous system toxicity is caused by short exposure to high partial pressures of oxygen at greater than atmospheric pressure. Pulmonary and ocular toxicity result from longer exposure to increased oxygen levels at normal pressure. Symptoms may include disorientation, breathing problems, and vision changes such as myopia. Prolonged exposure to above-normal oxygen partial pressures, or shorter exposures to very high partial pressures, can cause oxidative damage to cell membranes, collapse of the alveoli in the lungs, retinal detachment, and seizures. Oxygen toxicity is managed by reducing the exposure to increased oxygen levels.
Oxygen toxicity | Introduction
Although oxygen is essential to life, in concentrations significantly greater than normal it becomes toxic, overcoming the body's natural defences (antioxidants), and causing cell death in any part of the body. The lungs and brain are particularly affected by high partial pressures of oxygen, such as are encountered in diving. The body can tolerate partial pressures of oxygen around indefinitely, and up to for many hours, but higher partial pressures rapidly increase the chance of the most dangerous effect of oxygen toxicity, a convulsion resembling an epileptic seizure. Susceptibility to oxygen toxicity varies dramatically from person to person, and to a smaller extent from day to day for the same diver.
Diving medicine | Oxygen toxicity
"o"-Tolylthiourea is a highly toxic chemical compound.
O-Tolylthiourea | Introduction
Oxygen is a colourless, odourless, and unpredictably reactive diatomic gas with a gaseous density of 1.429 × 10 g/cm (marginally heavier than air). It is generally unreactive at room temperature. Thus, sodium metal will "retain its metallic lustre for days in the presence of absolutely dry air and can even be melted (m.p. 97.82 °C) in the presence of dry oxygen without igniting". On the other hand, oxygen can react with many inorganic and organic compounds either spontaneously or under the right conditions, (such as a flame or a spark) [or ultra-violet light?]. It condenses to pale blue liquid −182.962 °C and freezes into a light blue solid at −218.79 °C.
Nonmetal | Group 16
Typical [NiFe] hydrogenases like those of "D. vulgaris" and "D. gigas" are poisoned by oxygen because an oxygen atom binds strongly to the NiFe active site.
Cupriavidus necator | Typical anaerobic [Ni-Fe] hydrogenases
Hexachloropropene is a toxic compound of chlorine and carbon. Its linear formula is CClCCl=CCl.
Hexachloropropene | Introduction
For this reason it is also called yellow phosphorus. It glows greenish in the dark (when exposed to oxygen) and is highly flammable and pyrophoric (self-igniting) upon contact with air. It is toxic, causing severe liver damage on ingestion and phossy jaw from chronic ingestion or inhalation. The odour of combustion of this form has a characteristic garlic smell, and samples are commonly coated with white "diphosphorus pentoxide", which consists of PO tetrahedral with oxygen inserted between the phosphorus atoms and at their vertices. White phosphorus is only slightly soluble in water and can be stored under water. Indeed, white phosphorus is safe from self-igniting only when it is submerged in water.
Allotropes of phosphorus | White phosphorus
Because they are strongly oxidative, many oxygen–xenon compounds are toxic; they are also explosive (highly exothermic), breaking down to elemental xenon and diatomic oxygen (O) with much stronger chemical bonds than the xenon compounds. Xenon gas can be safely kept in normal sealed glass or metal containers at standard temperature and pressure. However, it readily dissolves in most plastics and rubber, and will gradually escape from a container sealed with such materials. Xenon is non-toxic, although it does dissolve in blood and belongs to a select group of substances that penetrate the blood–brain barrier, causing mild to full surgical anesthesia when inhaled in high concentrations with oxygen.
Xenon | Precautions
Little precaution is necessary with the oxide but, after exposure to H, the resulting platinum black can be pyrophoric. Therefore, it should not be allowed to dry and all exposure to oxygen should be minimized.
Adams' catalyst | Safety
The magnetic properties of oxygen have been studied extensively. At very high pressures, solid oxygen changes from an insulating to a metallic state; and at very low temperatures, it even transforms to a superconducting state. Structural investigations of solid oxygen began in the 1920s and, at present, six distinct crystallographic phases are established unambiguously. The density of solid oxygen ranges from 21 cm/mol in the α-phase, to 23.5 cm/mol in the γ-phase.
Solid oxygen | Introduction
NO is a strong oxidizer that forms explosive mixtures with organic compounds and ammonium salts. The decomposition of dinitrogen pentoxide produces the highly toxic nitrogen dioxide gas.
Dinitrogen pentoxide | Hazards
Bronchopulmonary dysplasia is reversible in the early stages by use of break periods on lower pressures of oxygen, but it may eventually result in irreversible lung injury if allowed to progress to severe damage. One or two days of exposure without oxygen breaks are needed to cause such damage. Retinopathy of prematurity is largely preventable by screening. Current guidelines require that all babies of less than 32 weeks gestational age or having a birth weight less than should be screened for retinopathy of prematurity at least every two weeks. The "National Cooperative Study" in 1954 showed a causal link between supplemental oxygen and retinopathy of prematurity, but subsequent curtailment of supplemental oxygen caused an increase in infant mortality.
Oxygen toxicity | Normobaric setting
Exposures, from minutes to a few hours, to partial pressures of oxygen above —about eight times normal atmospheric partial pressure—are usually associated with central nervous system oxygen toxicity and are most likely to occur among patients undergoing hyperbaric oxygen therapy and divers. Since sea level atmospheric pressure is about , central nervous system toxicity can only occur under hyperbaric conditions, where ambient pressure is above normal. Divers breathing air at depths beyond face an increasing risk of an oxygen toxicity "hit" (seizure). Divers breathing a gas mixture enriched with oxygen, such as nitrox, can similarly suffer a seizure at shallower depths, should they descend below the maximum operating depth allowed for the mixture.
Oxygen toxicity | Central nervous system toxicity
Another possibility to stabilize this form of oxygen is to produce it inside confined spaces, e.g., fullerene.
Cyclic ozone | Introduction
The convulsion caused by oxygen toxicity does not lead to hypoxia, a side effect common to most seizures, because the body has an excess amount of oxygen when the convulsion begins. The seizures can lead to drowning, however, if the convulsion is suffered by a diver still in the water. Prolonged exposure to higher oxygen levels at atmospheric pressure can lead to pulmonary and ocular toxicity. Symptoms of oxygen toxicity may include disorientation, respiratory problems, or myopia. Prolonged exposure to higher than normal partial pressures of oxygen can result in oxidative damage to cell membranes. Signs of pulmonary (lung) oxygen toxicity begin with slight irritation in the trachea.
Hyperoxia | Oxygen toxicity
This is an example of histotoxic hypoxia. The most hazardous compound is hydrogen cyanide, which is a gas and kills by inhalation. For this reason, an air respirator supplied by an external oxygen source must be worn when working with hydrogen cyanide. Hydrogen cyanide is produced by adding acid to a solution containing a cyanide salt. Alkaline solutions of cyanide are safer to use because they do not evolve hydrogen cyanide gas. Hydrogen cyanide may be produced in the combustion of polyurethanes; for this reason, polyurethanes are not recommended for use in domestic and aircraft furniture. Oral ingestion of a small quantity of solid cyanide or a cyanide solution as little as 200 mg, or exposure to airborne cyanide of 270 ppm, is sufficient to cause death within minutes.
Cyanide | Toxicity
Liquid oxygen has a pale blue color and is strongly paramagnetic: it can be suspended between the poles of a powerful +U- magnet (horseshoe). Liquid oxygen has a density of 1.141 g/cm (1.141 kg/L or 1141 kg/m), slightly denser than liquid water, and is cryogenic with a freezing point of and a boiling point of at 101.325 kPa (760 mmHg). Liquid oxygen has an expansion ratio of 1:861 under and , and because of this, it is used in some commercial and military aircraft as a transportable source of breathing oxygen. Because of its cryogenic nature, liquid oxygen can cause the materials it touches to become extremely brittle.
Liquid oxygen | Physical properties
Chemical oxygen generators store oxygen in their chemical composition, and can be used only one time. "Oxygen Candles" contain a mix of sodium chlorate and iron powder, which when ignited smolders at about 600 °C (1,112 °F) and results in sodium chloride, iron oxide, and oxygen, about 270 liters per kg of mixture. Some commercial airliners use emergency oxygen generators containing a mixture of sodium chlorate (NaClO), 5 percent barium peroxide (BaO) and 1 percent potassium perchlorate (KClO), which after ignition, reacts releasing oxygen for 12 to 22 minutes while the unit reaches .
Oxygen storage | Chemical oxygen generators
Supplemental oxygen exposure, while a risk factor, is not the main risk factor for development of this disease. Restricting supplemental oxygen use does not necessarily reduce the rate of retinopathy of prematurity, and may raise the risk of hypoxia-related systemic complications. Hyperoxic myopia has occurred in closed circuit oxygen rebreather divers with prolonged exposures. It also occurs frequently in those undergoing repeated hyperbaric oxygen therapy. This is due to an increase in the refractive power of the lens, since axial length and keratometry readings do not reveal a corneal or length basis for a myopic shift. It is usually reversible with time.
Oxygen toxicity | Ocular toxicity
The substance decomposes upon combustion with the formation of toxic gases, including sulfur oxides. It reacts violently with strong oxidizing agents, acids, reducing agents, and metals.
Hexadecanethiol | Toxicology and safety
Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as or ), which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambient temperature, however the rate of decay is slow. The lowest excited state of the diatomic oxygen molecule is a singlet state. It is a gas with physical properties differing only subtly from those of the more prevalent triplet ground state of O. In terms of its chemical reactivity, however, singlet oxygen is far more reactive toward organic compounds. It is responsible for the photodegradation of many materials but can be put to constructive use in preparative organic chemistry and photodynamic therapy.
Singlet oxygen | Introduction
Oxygen condenses at 90.20 K (−182.95 °C, −297.31 °F), and freezes at 54.36 K (−218.79 °C, −361.82 °F). Both liquid and solid are clear substances with a light sky-blue color caused by absorption in the red (in contrast with the blue color of the sky, which is due to Rayleigh scattering of blue light). High-purity liquid is usually obtained by the fractional distillation of liquefied air. Liquid oxygen may also be condensed from air using liquid nitrogen as a coolant. Oxygen is a highly reactive substance and must be segregated from combustible materials.
Oxygen | Physical properties
Thallium(I) oxide, like all thallium compounds, is highly toxic.
Thallium(I) oxide | Introduction
An alternate stable form, if it exists, may appear at pressures of at least 50 GPa and temperatures of at least 1,500 K; it has been thought to have an orthorhombic or a double hcp structure. as of December 2011, recent and ongoing experiments are being conducted on high-pressure and Superdense carbon allotropes.
Allotropes of iron | Experimental high temperature and pressure
Because it is easily oxidized it must be kept under vacuum. Tetraborane ignites when it comes in contact with air, oxygen, and nitric acid. Boranes in general including tetraborane have been deemed very toxic and are biologically destructive. A study consisting of small daily exposure of the chemical to rabbits and rats resulted in fatality.
Tetraborane | Safety
Fe(CO) is hazardous as a source of volatile iron and as a source of carbon monoxide. Solid samples, especially when finely divided, and residues from reactions can be pyrophoric, which can ignite the organic solvents used for such reactions.
Triiron dodecacarbonyl | Safety
Potassium hydrogenoxalate is strongly irritating to eyes, mucoses and gastrointestinal tract. It may cause cardiac failure and death.
Potassium hydrogenoxalate | Toxicity
OF is a viscous, blood-red liquid. It remains liquid at 90 K and so can be differentiated from OF which has a melting point of about 109 K. Like the other oxygen fluorides, OF is endothermic and decomposes at about 115 K with the evolution of heat, which is given by the following reaction: OF is safer to work with than ozone, and can be evaporated, or thermally decomposed, or exposed to electric sparks, without any explosions. But on contact with organic matter or oxidizable compounds, it can detonate or explode. Thus, the addition of even one drop of ozone difluoride to solid anhydrous ammonia will result in a mild explosion, when they are both at 90 K each.
Oxygen fluoride | Trioxygen difluoride (OF)
Atomic oxygen, denoted O(P) or O(3P), is very reactive, as the single atoms of oxygen tend to quickly bond with nearby molecules. On Earth's surface, it does not exist naturally for very long, but in outer space, the presence of plenty of ultraviolet radiation results in a low Earth orbit atmosphere in which 96% of the oxygen occurs in atomic form. Atomic oxygen has been detected on Mars by Mariner, Viking, and the SOFIA observatory.
Allotropes of oxygen | Atomic oxygen
Six different phases of solid oxygen are known to exist: It has been known that oxygen is solidified into a state called the β-phase at room temperature by applying pressure, and with further increasing pressure, the β-phase undergoes phase transitions to the δ-phase at 9 GPa and the ε-phase at 10 GPa; and, due to the increase in molecular interactions, the color of the β-phase changes to pink, orange, then red (the stable octaoxygen phase), and the red color further darkens to black with increasing pressure. It was found that a metallic ζ-phase appears at 96 GPa when ε-phase oxygen is further compressed.
Solid oxygen | Phases
Diving with and handling nitrox raise a number of potentially fatal dangers due to the high partial pressure of oxygen (ppO). Nitrox is not a deep-diving gas mixture owing to the increased proportion of oxygen, which becomes toxic when breathed at high pressure. For example, the maximum operating depth of nitrox with 36% oxygen, a popular recreational diving mix, is to ensure a maximum ppO of no more than . The exact value of the maximum allowed ppO and maximum operating depth varies depending on factors such as the training agency, the type of dive, the breathing equipment and the level of surface support, with professional divers sometimes being allowed to breathe higher ppO than those recommended to recreational divers.
Nitrox | Oxygen toxicity
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'.
Allotropes of oxygen | Ozone
X-rays of the lungs show little change in the short term, but extended exposure leads to increasing diffuse shadowing throughout both lungs. Pulmonary function measurements are reduced, as noted by a reduction in the amount of air that the lungs can hold (vital capacity) and changes in expiratory function and lung elasticity. Tests in animals have indicated a variation in tolerance similar to that found in central nervous system toxicity, as well as significant variations between species. When the exposure to oxygen above is intermittent, it permits the lungs to recover and delays the onset of toxicity.
Oxygen toxicity | Lungs
At room temperature, ethane is an extremely flammable gas. When mixed with air at 3.0%–12.5% by volume, it forms an explosive mixture. Some additional precautions are necessary where ethane is stored as a cryogenic liquid. Direct contact with liquid ethane can result in severe frostbite. Until they warm to room temperature, the vapors from liquid ethane are heavier than air and can flow along the floor or ground, gathering in low places; if the vapors encounter an ignition source, the chemical reaction can flash back to the source of ethane from which they evaporated. Ethane can displace oxygen and become an asphyxiation hazard.
Ethane | Health and safety
Ozone is produced in the upper atmosphere when combines with atomic oxygen made by the splitting of by ultraviolet (UV) radiation. Since ozone absorbs strongly in the UV region of the spectrum, the ozone layer of the upper atmosphere functions as a protective radiation shield for the planet. Near the Earth's surface, it is a pollutant formed as a by-product of automobile exhaust. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft. The metastable molecule tetraoxygen () was discovered in 2001, and was assumed to exist in one of the six phases of solid oxygen.
Oxygen | Allotropes