Halothane, sold under the brand name Fluothane among others, is a general anesthetic. It can be used to maintain anaesthesia. One of its benefits is that it does not increase the production of saliva, which can be useful in those who are difficult to intubate, it is given by inhalation. Side effects include an irregular heartbeat, decreased effort to breathe, liver problems. Like all volatile anesthetics, it should not be used in people with a personal or family history of malignant hyperthermia, it appears to be safe in porphyria. It is unclear whether use during pregnancy is harmful to the baby, it is not recommended for use during a C-section. Halothane is a chiral molecule, used as a racemic mixture. Halothane was discovered in 1955, it is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. As of 2014, the wholesale cost in the developing world is about 22 to 52 USD for a 250 mL bottle, its use in developed countries has been replaced by newer anesthetic agents such as sevoflurane.
It is no longer commercially available in the United States. Halothane contributes to ozone depletion, it is a potent anesthetic with a MAC of 0.74%. Its blood/gas partition coefficient of 2.4 makes it an agent with moderate induction and recovery time. It is not a good analgesic and its muscle relaxation effect is moderate. In rare cases, repeated exposure to halothane in adults was noted to result in severe liver injury; this occurred in about one in 10,000 exposures. The resulting syndrome was referred to as halothane hepatitis, is thought to result from the metabolism of halothane to trifluoroacetic acid via oxidative reactions in the liver. About 20% of inhaled halothane is metabolized by the liver and these products are excreted in the urine; the hepatitis syndrome had a mortality rate of 30% to 70%. Concern for hepatitis resulted in a dramatic reduction in the use of halothane for adults and it was replaced in the 1980s by enflurane and isoflurane. By 2005, the most common volatile anesthetics used were isoflurane and desflurane.
Since the risk of halothane hepatitis in children was lower than in adults, halothane continued to be used in pediatrics in the 1990s as it was useful for inhalation induction of anaesthesia. However, by 2000, excellent for inhalation induction, had replaced the use of halothane in children. Halothane sensitises the heart to catecholamines, so it is liable to cause cardiac arrhythmias fatal if hypercapnia has been allowed to develop; this seems to be problematic in dental anaesthesia. Like all the potent inhalational anaesthetic agents, it is a potent trigger for malignant hyperthermia. In common with the other potent inhalational agents, it relaxes uterine smooth muscle and this may increase blood loss during delivery or termination of pregnancy. People can be exposed to halothane in the workplace by breathing it in as waste anaesthetic gas, skin contact, eye contact, or swallowing it; the National Institute for Occupational Safety and Health has set a recommended exposure limit of 2 ppm over 60 minutes.
Halothane activates glycine receptors. It acts as an NMDA receptor antagonist, inhibits nACh and voltage-gated sodium channels, activates 5-HT3 and twin-pore K+ channels, it does not affect the AMPA or kainate receptors. Chemically, halothane is an alkyl halide; the structure has one stereocenter, so - and -optical isomers occur. The commercial synthesis of halothane starts from trichloroethylene, reacted with hydrogen fluoride in the presence of antimony trichloride at 130 °C to form 2-chloro-1,1,1-trifluoroethane; this is reacted with bromine at 450 °C to produce halothane. Attempts to find anesthetics with less metabolism led to halogenated ethers such as enflurane and isoflurane; the incidence of hepatic reactions with these agents is lower. The exact degree of hepatotoxic potential of enflurane is debated, although it is minimally metabolized. Isoflurane is not metabolized and reports of associated liver injury are quite rare. Small amounts of trifluoroacetic acid can be formed from both halothane and isoflurane metabolism and accounts for cross sensitization of patients between these agents.
The main advantage of the more modern agents is lower blood solubility, resulting in faster induction of and recovery from anaesthesia. Halothane was first synthesized by C. W. Suckling of Imperial Chemical Industries in 1951 in Widnes and was first used clinically by M. Johnstone in Manchester in 1956, it became popular as a nonflammable general anesthetic replacing other volatile anesthetics such as trichloroethylene, diethyl ether and cyclopropane. In many parts of the world it has been replaced by newer agents since the 1980s but is still used in developing countries and in veterinary surgery because of its lower cost. Halothane was given to many millions of adult and pediatric patients worldwide from its introduction in 1956 through the 1980s, its properties include cardiac depression at high levels, cardiac sensitization to catecholamines such as norepinephrine, potent bronchial relaxation. Its lack of airway irritation made it a common inhalation induction agent in pediatric anesthesia.
Due to its cardiac depressive effect, it was contraindicated in patients with cardiac failure. Halothane was contraindicated in patients susceptible to cardiac arrhythmias, or in situations related to high catecholamine levels such as pheochromocytoma, it is available as a volatile liquid, at 30, 50, 200, 250 ml per container but in many developed nations is not available having been displa
Mealworms are the larval form of the mealworm beetle, Tenebrio molitor, a species of darkling beetle. Like all holometabolic insects, they go through four life stages: egg, larva and adult. Larvae measure about 2.5 cm or more, whereas adults are between 1.25 and 1.8 cm in length. The mealworm beetle breeds prolifically. Mating is a three-step process: the male chasing the female, mounting her and inserting his aedeagus, injecting a sperm packet. Within a few days the female lays about 500 eggs. After four to 19 days the eggs hatch. Many predators target the eggs, including reptiles. During the larval stage, the mealworm feeds on vegetation and dead insects and molts between each larval stage, or instar. After the final molt it becomes a pupa; the new pupa is whitish, it turns brown over time. After 3 to 30 days, depending on environmental conditions such as temperature, it emerges as an adult beetle. A sex pheromone released by male mealworms has been identified. Inbreeding reduces the attractiveness of sexual pheromone signaling by male mealworms.
Females are more attracted to the odors produced by outbred males than the odors produced by inbred males. The reduction of male signaling capability may be due to increased expression of homozygous deleterious recessive alleles caused by inbreeding. Tenebrio molitor is used for biological research, its large size, ease of rearing and handling, status as a non-model organism make it useful in proof of concept studies in the fields of basic biology, evolution and physiology. Mealworms have been considered pests, because their larvae feed on stored grains. Mealworms originated in the Mediterranean region, but are now present in many areas of the world as a result of human trade and colonization; the oldest archaeological records of mealworms can be traced to Bronze Age Turkey. Records from the British Isles and northern Europe are from a date, mealworms are conspicuously absent from archaeological finds from ancient Egypt. Mealworms are edible for humans, are consumed in a practice known as entomophagy.
Mealworms have been consumed in many Asian countries in Southeast Asia. They are found in food markets and sold as street food alongside other edible insects. Baked or fried mealworms have been marketed as a healthy snack food in recent history, though the consumption of mealworms goes back centuries, they may be reared on fresh oats, wheat bran or grain, with sliced potato, carrots, or apple as a moisture source. The small amount of space required to raise mealworms has made them popular in many parts of Southeast Asia. Mealworms have been incorporated into tequila-flavored novelty candies. Mealworms are not traditionally served in tequila, the "tequila worm" in certain mezcals is the larva of the moth Hypopta agavis. Mealworms are used as a pet food for captive reptiles and birds, they are provided to wild birds in bird feeders during the nesting season. Mealworms are useful for their high protein content, they are used as fishing bait. They are commercially available in bulk and are available in containers with bran or oatmeal for food.
Commercial growers incorporate a juvenile hormone into the feeding process to keep the mealworm in the larval stage and achieve an abnormal length of 2 cm or greater. Mealworm larva contain significant nutrient content, a feature that has made them viable as food and feed. For every 100 grams of raw mealworm larva, 206 calories and anywhere from 14 to 25 grams of protein are contained. Mealworm larva contain levels of potassium, sodium, selenium and zinc that rival that of beef. Mealworms contain essential linoleic acids as well, they have greater vitamin content by weight compared to beef, B12 not included. In 2015, it was discovered that mealworms are capable of degrading polystyrene into usable organic matter at a rate of about 34-39 milligrams per day. Additionally, no difference was found between mealworms fed only styrofoam and mealworms fed conventional foods, during the one-month duration of the experiment. Microorganisms inside the mealworm's gut are responsible for degrading the polystyrene, with mealworms given the antibiotic gentamicin showing no signs of degradation.
Isolated colonies of the mealworm's gut microbes, have proven less efficient at degradation than the bacteria within the gut. No attempts to commercialize this discovery have been made. Zond 5, a 1968 space mission on which mealworms were among the first earthlings to fly to the Moon Darkling Beetle/Mealworm Information. Center for Insect Science Education Outreach. University of Arizona. Mealworms and Darkling Beetles. FOSSweb. Mealworms.org
Dielectric heating known as electronic heating, radio frequency heating, high-frequency heating, is the process in which a radio frequency alternating electric field, or radio wave or microwave electromagnetic radiation heats a dielectric material. At higher frequencies, this heating is caused by molecular dipole rotation within the dielectric. RF dielectric heating at intermediate frequencies, due to its greater penetration over microwave heating, shows greater promise than microwave systems as a method of rapidly heating and uniformly preparing certain food items, killing parasites and pests in certain harvested crops. Molecular rotation occurs in materials containing polar molecules having an electrical dipole moment, with the consequence that they will align themselves in an electromagnetic field. If the field is oscillating, as it is in an electromagnetic wave or in a oscillating electric field, these molecules rotate continuously by aligning with it; this is called dipolar polarisation.
As the field alternates, the molecules reverse direction. Rotating molecules push and collide with other molecules, distributing the energy to adjacent molecules and atoms in the material; the process of energy transfer from the source to the sample is a form of radiative heating. Temperature is related to the average kinetic energy of the atoms or molecules in a material, so agitating the molecules in this way increases the temperature of the material. Thus, dipole rotation is a mechanism by which energy in the form of electromagnetic radiation can raise the temperature of an object. There are many other mechanisms by which this conversion occurs. Dipole rotation is the mechanism referred to as dielectric heating, is most observable in the microwave oven where it operates most efficaciously on liquid water, but much less so, on fats and sugars; this is because fats and sugar molecules are far less polar than water molecules, thus less affected by the forces generated by the alternating electromagnetic fields.
Outside of cooking, the effect can be used to heat solids, liquids, or gases, provided they contain some electric dipoles. Dielectric heating involves the heating of electrically insulating materials by dielectric loss. A changing electric field across the material causes energy to be dissipated as the molecules attempt to line up with the continuously changing electric field; this changing electric field may be caused by an electromagnetic wave propagating in free space, or it may be caused by a alternating electric field inside a capacitor. In the latter case, there is no freely-propagating electromagnetic wave, the changing electric field may be seen as analogous to the electric component of an antenna near field. In this case, although the heating is accomplished by changing the electric field inside the capacitive cavity at radio-frequency frequencies, no actual radio waves are either generated or absorbed. In this sense, the effect is the direct electrical analog of magnetic induction heating, near-field effect.
Frequencies in the range of 10–100 MHz are necessary to cause dielectric heating, although higher frequencies work well or better, in some materials lower frequencies have significant heating effects due to more unusual mechanisms. For example, in conductive liquids such as salt water, ion-drag causes heating, as charged ions are "dragged" more back and forth in the liquid under influence of the electric field, striking liquid molecules in the process and transferring kinetic energy to them, translated into molecular vibrations and thus into thermal energy. Dielectric heating at low frequencies, as a near-field effect, requires a distance from electromagnetic radiator to absorber of less than 1/2π ≈ 1/6 of a wavelength, it is thus a contact process or near-contact process, since it sandwiches the material to be heated between metal plates taking the place of the dielectric in what is a large capacitor. However, actual electrical contact is not necessary for heating a dielectric inside a capacitor, as the electric fields that form inside a capacitor subjected to a voltage do not require electrical contact of the capacitor plates with the dielectric material between the plates.
Because lower frequency electrical fields penetrate non-conductive materials far more than do microwaves, heating pockets of water and organisms deep inside dry materials like wood, it can be used to heat and prepare many non-electrically conducting food and agricultural items, so long as they fit between the capacitor plates. At high frequencies, the wavelength of the electromagnetic field becomes shorter than the distance between the metal walls of the heating cavity, or than the dimensions of the walls themselves; this is the case inside a microwave oven. In such cases, conventional far-field electromagnetic waves form, are absorbed to cause heating, but the dipole-rotation mechanism of heat deposition remains the same. However, microwaves are not efficient at causing the heating effects of low frequency fields that depend on slower molecular motion, such as those caused by ion-drag. Dielectric heating must be distinguished from Joule heating of conductive media, caused by induced electric currents in the media.
For dielectric heating, the generated power density per volume is given by: Q = ω ⋅ ε r ″ ⋅ ε 0 ⋅ E
Chloroform, or trichloromethane, is an organic compound with formula CHCl3. It is a colorless, sweet-smelling, dense liquid, produced on a large scale as a precursor to PTFE, it is a precursor to various refrigerants. It is one of a trihalomethane, it is a powerful anesthetic, euphoriant and sedative when inhaled or ingested. The molecule adopts a tetrahedral molecular geometry with C3v symmetry; the total global flux of chloroform through the environment is 660000 tonnes per year, about 90% of emissions are natural in origin. Many kinds of seaweed produce chloroform, fungi are believed to produce chloroform in soil. Abiotic process is believed to contribute to natural chloroform productions in soils although the mechanism is still unclear. Chloroform volatilizes from soil and surface water and undergoes degradation in air to produce phosgene, formyl chloride, carbon monoxide, carbon dioxide, hydrogen chloride, its half-life in air ranges from 55 to 620 days. Biodegradation in water and soil is slow.
Chloroform does not bioaccumulate in aquatic organisms. Chloroform was synthesized independently by several investigators circa 1831: Moldenhawer, a German pharmacist from Frankfurt an der Oder, appears to have produced chloroform in 1830 by mixing chlorinated lime with ethanol. Samuel Guthrie, an American physician from Sackets Harbor, New York appears to have produced chloroform in 1831 by reacting chlorinated lime with ethanol, as well as noting its anaesthetic properties. Justus von Liebig carried out the alkaline cleavage of chloral. Eugène Soubeiran obtained the compound by the action of chlorine bleach on both acetone. In 1834, French chemist Jean-Baptiste Dumas named it. In 1835, Dumas prepared the substance by the alkaline cleavage of trichloroacetic acid. Regnault prepared chloroform by chlorination of chloromethane. In 1842, Robert Mortimer Glover in London discovered the anaesthetic qualities of chloroform on laboratory animals. In 1847, Scottish obstetrician James Y. Simpson was the first to demonstrate the anaesthetic properties of chloroform on humans and helped to popularise the drug for use in medicine.
By the 1850s, chloroform was being produced on a commercial basis by using the Liebig procedure, which retained its importance until the 1960s. Today, chloroform — along with dichloromethane — is prepared and on a massive scale by the chlorination of methane and chloromethane. In industry, chloroform is produced by heating a mixture of chlorine and either chloromethane or methane. At 400–500 °C, a free radical halogenation occurs, converting these precursors to progressively more chlorinated compounds: CH4 + Cl2 → CH3Cl + HCl CH3Cl + Cl2 → CH2Cl2 + HCl CH2Cl2 + Cl2 → CHCl3 + HClChloroform undergoes further chlorination to yield carbon tetrachloride: CHCl3 + Cl2 → CCl4 + HClThe output of this process is a mixture of the four chloromethanes, which can be separated by distillation. Chloroform may be produced on a small scale via the haloform reaction between acetone and sodium hypochlorite: 3 NaClO + 2CO → CHCl3 + 2 NaOH + NaOCOCH3 Deuterated chloroform is an isotopologue of chloroform with a single deuterium atom.
CDCl3 is a common solvent used in NMR spectroscopy. Deuterochloroform is produced by the haloform reaction, the reaction of acetone with sodium hypochlorite or calcium hypochlorite; the haloform process is now obsolete for the production of ordinary chloroform. Deuterochloroform can be prepared by the reaction of sodium deuteroxide with chloral hydrate; the haloform reaction can occur inadvertently in domestic settings. Bleaching with hypochlorite generates halogenated compounds in side reactions. Sodium hypochlorite solution mixed with common household liquids such as acetone, methyl ethyl ketone, ethanol, or isopropyl alcohol can produce some chloroform, in addition to other compounds such as chloroacetone or dichloroacetone. In terms of scale, the most important reaction of chloroform is with hydrogen fluoride to give monochlorodifluoromethane, a precursor in the production of polytetrafluoroethylene: CHCl3 + 2 HF → CHClF2 + 2 HClThe reaction is conducted in the presence of a catalytic amount of mixed antimony halides.
Chlorodifluoromethane is converted into tetrafluoroethylene, the main precursor to Teflon. Before the Montreal Protocol, chlorodifluoromethane was a popular refrigerant; the hydrogen attached to carbon in chloroform participates in hydrogen bonding. Worldwide, chloroform is used in pesticide formulations, as a solvent for fats, rubber, waxes, gutta-percha, resins, as a cleansing agent, grain fumigant, in fire extinguishers, in the rubber industry. CDCl3 is a common solvent used in NMR spectroscopy; as a reagent, chloroform serves as a source of the dichlorocarbene CCl2 group. It reacts with aqueous sodium hydroxide in the presence of a phase transfer catalyst to produce dichlorocarbene, CCl2; this reagent effects ortho-formylation of activated aromatic rings such as phenols, producing aryl aldehydes in a reaction known as the Reimer–Tiemann reaction. Alternatively, the carbene can be trapped by an alkene to form a cyclopropane derivative. In the Kharasch addition, chloroform forms the CHCl2 free radical in addition to alkenes.
The anaesthetic qualities of chloroform were first described in 1842 in a thesis by Robert Mortimer Glover, which won t
Manchester is a city and metropolitan borough in Greater Manchester, with a population of 545,500 as of 2017. It lies within the United Kingdom's second-most populous built-up area, with a population of 3.2 million. It is fringed by the Cheshire Plain to the south, the Pennines to the north and east, an arc of towns with which it forms a continuous conurbation; the local authority is Manchester City Council. The recorded history of Manchester began with the civilian settlement associated with the Roman fort of Mamucium or Mancunium, established in about AD 79 on a sandstone bluff near the confluence of the rivers Medlock and Irwell, it was a part of Lancashire, although areas of Cheshire south of the River Mersey were incorporated in the 20th century. The first to be included, was added to the city in 1931. Throughout the Middle Ages Manchester remained a manorial township, but began to expand "at an astonishing rate" around the turn of the 19th century. Manchester's unplanned urbanisation was brought on by a boom in textile manufacture during the Industrial Revolution, resulted in it becoming the world's first industrialised city.
Manchester achieved city status in 1853. The Manchester Ship Canal opened in 1894, creating the Port of Manchester and directly linking the city to the Irish Sea, 36 miles to the west, its fortune declined after the Second World War, owing to deindustrialisation, but the IRA bombing in 1996 led to extensive investment and regeneration. In 2014, the Globalisation and World Cities Research Network ranked Manchester as a beta world city, the highest-ranked British city apart from London. Manchester is the third-most visited city after London and Edinburgh, it is notable for its architecture, musical exports, media links and engineering output, social impact, sports clubs and transport connections. Manchester Liverpool Road railway station was the world's first inter-city passenger railway station. Manchester hosted the 2002 Commonwealth Games; the name Manchester originates from the Latin name Mamucium or its variant Mancunium and the citizens are still referred to as Mancunians. These are thought to represent a Latinisation of an original Brittonic name, either from mamm- or from mamma.
Both meanings are preserved in Insular Celtic languages, such as mam meaning "breast" in Irish and "mother" in Welsh. The suffix -chester is a survival of Old English ceaster and from that castra in latin for camp or settlement; the Brigantes were the major Celtic tribe in. Their territory extended across the fertile lowland of what is now Stretford. Following the Roman conquest of Britain in the 1st century, General Agricola ordered the construction of a fort named Mamucium in the year 79 to ensure that Roman interests in Deva Victrix and Eboracum were protected from the Brigantes. Central Manchester has been permanently settled since this time. A stabilised fragment of foundations of the final version of the Roman fort is visible in Castlefield; the Roman habitation of Manchester ended around the 3rd century. After the Roman withdrawal and Saxon conquest, the focus of settlement shifted to the confluence of the Irwell and Irk sometime before the arrival of the Normans after 1066. Much of the wider area was laid waste in the subsequent Harrying of the North.
Thomas de la Warre, lord of the manor and constructed a collegiate church for the parish in 1421. The church is now Manchester Cathedral; the library, which opened in 1653 and is still open to the public today, is the oldest free public reference library in the United Kingdom. Manchester is mentioned as having a market in 1282. Around the 14th century, Manchester received an influx of Flemish weavers, sometimes credited as the foundation of the region's textile industry. Manchester became an important centre for the manufacture and trade of woollens and linen, by about 1540, had expanded to become, in John Leland's words, "The fairest, best builded and most populous town of all Lancashire." The cathedral and Chetham's buildings are the only significant survivors of Leland's Manchester. During the English Civil War Manchester favoured the Parliamentary interest. Although not long-lasting, Cromwell granted it the right to elect its own MP. Charles Worsley, who sat for the city for only a year, was appointed Major General for Lancashire and Staffordshire during the Rule of the Major Generals.
He was a diligent puritan, banning the celebration of Christmas. Significant quantities of cotton began to be used after about 1600, firstly in linen/cotton fustians, but by around 1750 pure cotton fabrics were being produced and cotton had overtaken wool in importance; the Irwell and Mersey were made navigable by 1736, opening a route from Manchester to the sea docks on the Mersey. The Bridgewater Canal, Britain's first wholly artificial waterway, was opened in 1761, bringing coal from mines at Worsley to central Manchester; the canal was extended to the Mersey at Runcorn by 1776. The combination of competition and improved efficiency halved th
The Oldershaw Academy
Oldershaw Academy is a secondary school located in the Liscard area of Wallasey, England and is a specialist Business and Enterprise College. Dr. John Oldershaw founded the school in 1920, it opened on 11 September 1920. Extensions to the school were opened on 4 June 1926; the first headteacher was Mr. H. G. Mayo, M. A, it was administered by the County Borough of Wallasey. By 1968 it had 700 pupils. Wallasey Grammar School was a separate establishment based on Withens Lane, which moved to Leasowe in 1967 and is now The Kingsway Academy. Having separate sections for boys and girls, with segregated teaching except for'A' Level courses, Oldershaw became a comprehensive school in 1968 retaining the name of Oldershaw Grammar School although for ages 13–18; the school included four'houses': Durham, York and Chester. Prior to this the houses of the boys' grammar school were defined as colours: Blue, Gold and Green whilst the girls' high school houses were Oak, Fir and Elm. Wirral Education Authority rationalised their middle school system in 1982, added an extra year to primary schools and two years into secondary schools.
To accommodate these two extra years Olderhaw was expanded to include a Lower School, under K. R. M. Williams, at the site of the old St. Hilda's School in Ormond Street; the current forms of the school are Fir, Cedar, Maple and Elm although in recent years Poplar has been replaced in favour of the form Beech. In 2018 due to popularity growth the Sycamore form was added; the school has just undergone major developments. The original sixth form building was demolished to make way for a brand new building. With this new building came a new uniform; the new uniform was designed to give Oldershaw a clear identity within the local community. In 2016 there was senior management restructuring and the governors took the unusual step of appointing two Headteacher's with no deputy Headteachers. On June 30, 2011, The Oldershaw School became an academy. Prof M. C. Bradbrook, Professor of English from 1965-76 of the University of Cambridge, Mistress of Girton College, Cambridge from 1968–76 Dickie Davies, television presenter, World of Sport Air Vice-Marshal John Feesey AFC, Station Commander from 1986-88 of RAF Wittering and Commander from 1989-91 of the Allied Air Forces Central Europe Fred Jarvis, General Secretary from 1975-89 of the National Union of Teachers, President from 1952-54 of the National Union of Students Dr Charles Suckling CBE, chemist who first synthesised Halothane, the main general anaesthetic gas from 1956 until the 1980s, when working at the General Chemical Division of ICI in 1951 Oldershaw Heritage Project School Web Site EduBase
Fluorine is a chemical element with symbol F and atomic number 9. It is the lightest halogen and exists as a toxic pale yellow diatomic gas at standard conditions; as the most electronegative element, it is reactive, as it reacts with all other elements, except for helium and neon. Among the elements, fluorine ranks 24th in universal 13th in terrestrial abundance. Fluorite, the primary mineral source of fluorine which gave the element its name, was first described in 1529. Proposed as an element in 1810, fluorine proved difficult and dangerous to separate from its compounds, several early experimenters died or sustained injuries from their attempts. Only in 1886 did French chemist Henri Moissan isolate elemental fluorine using low-temperature electrolysis, a process still employed for modern production. Industrial production of fluorine gas for uranium enrichment, its largest application, began during the Manhattan Project in World War II. Owing to the expense of refining pure fluorine, most commercial applications use fluorine compounds, with about half of mined fluorite used in steelmaking.
The rest of the fluorite is converted into corrosive hydrogen fluoride en route to various organic fluorides, or into cryolite, which plays a key role in aluminium refining. Molecules containing a Carbon–fluorine bond have high chemical and thermal stability. Pharmaceuticals such as atorvastatin and fluoxetine contain C-F bonds, the fluoride ion inhibits dental cavities, so finds use in toothpaste and water fluoridation. Global fluorochemical sales amount to more than US$15 billion a year. Fluorocarbon gases are greenhouse gases with global-warming potentials 100 to 20,000 times that of carbon dioxide. Organofluorine compounds persist in the environment due to the strength of the carbon–fluorine bond. Fluorine has no known metabolic role in mammals. Fluorine atoms have nine electrons, one fewer than neon, electron configuration 1s22s22p5: two electrons in a filled inner shell and seven in an outer shell requiring one more to be filled; the outer electrons are ineffective at nuclear shielding, experience a high effective nuclear charge of 9 − 2 = 7.
Fluorine's first ionization energy is third-highest among all elements, behind helium and neon, which complicates the removal of electrons from neutral fluorine atoms. It has a high electron affinity, second only to chlorine, tends to capture an electron to become isoelectronic with the noble gas neon. Fluorine atoms have a small covalent radius of around 60 picometers, similar to those of its period neighbors oxygen and neon; the bond energy of difluorine is much lower than that of either Cl2 or Br2 and similar to the cleaved peroxide bond. Conversely, bonds to other atoms are strong because of fluorine's high electronegativity. Unreactive substances like powdered steel, glass fragments, asbestos fibers react with cold fluorine gas. Reactions of elemental fluorine with metals require varying conditions. Alkali metals cause; some solid nonmetals react vigorously in liquid air temperature fluorine. Hydrogen sulfide and sulfur dioxide combine with fluorine, the latter sometimes explosively. Hydrogen, like some of the alkali metals, reacts explosively with fluorine.
Carbon, as lamp black, reacts at room temperature to yield fluoromethane. Graphite combines with fluorine above 400 °C to produce non-stoichiometric carbon monofluoride. Carbon dioxide and carbon monoxide react at or just above room temperature, whereas paraffins and other organic chemicals generate strong reactions: fully substituted haloalkanes such as carbon tetrachloride incombustible, may explode. Although nitrogen trifluoride is stable, nitrogen requires an electric discharge at elevated temperatures for reaction with fluorine to occur, due to the strong triple bond in elemental nitrogen. Oxygen does not combine with fluorine under ambient conditions, but can be made to react using electric discharge at low temperatures and pressures. Heavier halogens react with fluorine as does the noble gas radon. At room temperature, fluorine is a gas of diatomic molecules, pale yellow, it has a characteristic halogen-like biting odor detectable at 20 ppb. Fluorine condenses into a bright yellow liquid at −188 °C, a transition temperature similar to those of oxygen and nitrogen.
Fluorine has two solid forms, α- and β-fluorine. The latter crystallizes at −220 °C and is transparent and sof