Carbon (from Latin: carbo "coal") is a chemical element with the symbol C and atomic number 6. These are not metals and tetravalents - making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Three isotopes occur naturally, 12 C and 13 C becomes stable, while 14 C is a radionuclide, decomposed with a half-life of about 5,730 Ã, years. Carbon is one of several elements known since antiquity.
Carbon is the 15th most abundant element in the Earth's crust, and the fourth largest element in the universe by mass after hydrogen, helium, and oxygen. The abundance of carbon, the diversity of its unique organic compounds, and its unusual ability to form polymers at temperatures commonly found on Earth allow this element to function as a common element of all known life. It is the second most abundant element in the human body with mass (about 18.5%) after oxygen.
Carbon atoms can bind together in different ways, called allotropes of carbon. The best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary greatly with allotropic forms. For example, graphite is opaque and black while diamonds are very transparent. Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "???????" meaning "to write"), whereas diamonds are the hardest known natural ingredients. Graphite is a good conductor of electricity while diamonds have low electrical conductivity. Under normal conditions, diamonds, carbon nanotubes, and graphene have the highest thermal conductivity of all known materials. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form at standard temperature and pressure. They are chemically resistant and require high temperatures to react even with oxygen.
The most common carbon oxidation state in inorganic compounds is 4, whereas 2 is found in carbon monoxide and transition carbonyl metal complexes. The largest inorganic carbon sources are limestone, dolomite and carbon dioxide, but significant quantities occur in the organic deposits of coal, peat, oil, and methane clathrates. Carbon forms a large number of compounds, more than any other element, with nearly ten million compounds described to date, but that amount is just a fraction of the amount of theoretically possible compound under standard conditions. For this reason, carbon is often referred to as the "king of elements".
Video Carbon
Characteristics
Carbon allotropes include graphite, one of the most gentle known substances, and diamonds, the harshest natural substances. These bonds are easy with other small atoms, including other carbon atoms, and are capable of forming some stable covalent bonds with suitable multivalent atoms. Carbon is known to form nearly ten million different compounds, most of all chemical compounds. Carbon also has the highest sublimation point of all elements. At atmospheric pressure it has no melting point, since its triple point is at 10.8 Ã,  ± 0.2Ã, MPa and 4,600 Ã,  ± 300Ã, K (4,330 Ã,  ± 300 Ã,  ° C, 7,820 Ã,  ± 540Ã,  ° F), resulting in a sublime of about 3,900Ã, C. The graphite is much more reactive than diamond under standard conditions, although it is more thermodynamically stable, delocalized is much more vulnerable to attack. For example, graphite may be oxidized by hot concentrated nitric acid under standard conditions to a mellic acid, C 6 (CO 2 H) 6 , which maintains the unit hexagonal graphite while breaking down larger structures.
The carbon is sank in a carbon arc, which has a temperature of about 5800 K (5,530 ° C or 9,980 ° F). Thus, in spite of its allotropic form, the carbon remains solid at temperatures higher than metals with the highest melting point of tungsten or rumen. Although thermodynamics is susceptible to oxidation, carbon rejects oxidation more effectively than elements such as iron and copper, which are the weaker ones at room temperature.
Carbon is the sixth element, with electron ground-state configuration of 1s 2 2s 2 2p 2 , where the four outer electrons are the valence of the electron. The first four ionization energies, 1086.5, 2352.6, 4620.5 and 6222.7 kJ/mol, are much higher than the heavier 14-member elements. The electronegativity of the carbon is 2.5, much higher than the heavier group-14 elements (1.8-1.9), but closer to most of the nearby nonmetallic metal, as well as some second and third line transition metals. Carbon covalent radius is usually taken as 77.2 μm (C-C), 66.7 μm (C = C) and 60.3 μm (C C C), although this may vary depending on the coordination number and what carbon is bound. In general, the covalent radius decreases with lower coordination rates and higher bond order.
Carbon compounds form the basis of all known life on Earth, and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars. Despite forming an extraordinary variety of compounds, most forms of carbon are relatively inactive under normal conditions. At standard temperature and pressure, it holds all but the strongest oxidation. It does not react with any sulfuric acid, hydrochloric acid, chlorine or alkali. At high temperatures, the carbon reacts with oxygen to form carbon oxides and will rob the oxygen from the metal oxide to leave the elemental metal. This exothermic reaction is used in the iron and steel industry to melt iron and to control the carbon content of steel:
- Fe
3 O < span>
4 4 C (s) -> 3 Fe (s) 4 CO (g)
Carbon monoxide can be recycled to smell more iron:
- Fe
3 O < span>
4 4 CO (g) -> 3 Fe (s) 4 CO
2 (g)
with sulfur to form carbon disulfide and with steam in a coal-gas reaction: 2 O (g) -> CO (g) H 2 (g) .
Carbon combines with several metals at high temperatures to form metal carbides, such as cementite iron carbide in steel and tungsten carbide, widely used as abrasive materials and for making harsh tips for cutting tools.
The allotrope carbon system covers a variety of extremes:
Allotropes
Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes. The three relatively well-known carbon allotropes are amorphous carbon, graphite, and diamond. Once considered exotic, current fullerenes are commonly synthesized and used in research; they include buckyballs, carbon nanotubes, carbon nanograms and nanofibers. Several other exotic allotropes have also been discovered, such as lonsdaleite, glassy carbon, carbon nanofoam and linear acetylenic carbon (carbyne).
Graphene is a two-dimensional carbon sheet with atoms arranged in a hexagonal lattice. In 2009, graphene appears to be the strongest material ever tested. The process of separating it from graphite would require further technological development before being economical for industrial processes. If successful, graphene can be used in the construction of space elevators. It could also be used to safely store hydrogen for use in hydrogen-based engines in cars.
The amorphous form is a variety of carbon atoms in a glass state that is not crystalline, irregular, not stored in a crystalline macro structure. It is present as a powder, and is a major element of substances such as charcoal, soot (carbon black) and activated carbon. At normal pressure, carbon takes the form of graphite, in which each atom binds trigonally with the other three in a plane composed of a fused hexagonal ring, just as in aromatic hydrocarbons. The resulting network is 2-dimensional, and the resulting flat sheet is stacked and loosely bonded through a weak van der Waals force. This gives graphite softness and splitting properties (slip sheets easily pass through each other). Due to the delocalisation of one of the outermost electrons from each atom to form? -cloud, graphite conducts electricity, but only on the plane of each covalently bonded sheet. This results in lower bulk electrical conductivity for carbon than most metals. Delocalization also contributes to the energetic stability of graphite above the diamond at room temperature.
At very high pressures, carbon forms a more compact allotrope, diamond, having nearly twice the density of graphite. Here, each atom is tetrahedrally tethered to the other four, forming a 3-dimensional network of sixteen-membered crimson rings. Diamond has the same cubic structure as silicon and germanium, and because of the carbon-carbon bond strength, it is the harshest natural substance measured by resistance to scratches. Contrary to popular belief that "diamonds are forever" , they are thermodynamically unstable (< f G Ã, Â ° (diamond, 298Ã, K ) = 2.9 kJ/mol) under normal conditions (298 Â ° K, 10 5 Pa) and turned into graphite. Due to the high activation energy barrier, the transition to graphite is very slow at normal temperatures that are not too conspicuous. The lower left corner phase diagram for carbon has not been studied experimentally. However, the latest computational studies using the method of functional density theory reached the conclusion that as T -> 0 K and p -> 0 Pa , the diamond becomes more stable than graphite about 1.1 kJ/mol. In some conditions, carbon crystallizes as lonsdaleite, a hexagonal crystal lattice with all atoms binding to covalent and properties similar to diamonds.
Fullerenes is the formation of synthetic crystals with graphite-like structures, but instead of hexagon, fullerenes are formed from pentagons (or even heptagons) of carbon atoms. The missing (or additional) atoms pierce the sheets into balls, ellipses, or cylinders. The properties of fullerenes (divided into buckyballs, buckytubes, and nanobuds) have not been fully analyzed and represent an intense area of ​​research in nanomaterials. The names of "fullerene" and "buckyball" are given after Richard Buckminster Fuller, a geodesic dome popularizer, which resembles a fullerene structure. Buckyballs are large enough molecules formed entirely of carbon bound trigonally, forming spheroids (the most famous and the simplest is a C-shaped soccerball 60 buckminsterfullerene). Carbon nanotubes are structurally similar to buckyballs, except that each atom is bonded trigonally in a curved sheet that forms a hollow cylinder. Nanobuds were first reported in 2007 and are buckyball/buckyball hybrid materials (bov- ovally buckyballs bound to the outer walls of nanotubes) that combine the properties of both in a single structure.
Of the other allotropes found, carbon nanofoam is a ferromagnetic allotrope that was discovered in 1997. It consists of a cluster of low-density carbon clusters strung together in loose three-dimensional webs, in which atoms bind trigonally in six- and membered rings seven. It is one of the lightest solids, with a density of about 2 kg/m 3 . Similarly, carbon glass contains a high proportion of closed porosity, but contrary to normal graphite, the graphite layer is not stacked like the pages in the book, but has a more random arrangement. Acetylenic linear carbon has a chemical structure - (C ::: C) n -. The carbon in this modification is linear by the hybridization of orbitals sp , and is a polymer with a single bond and triplicate. Carbyne is very interesting for nanotechnology as its Young's modulus is 40 times that of the hardest matter - diamond.
By 2015, a team at North Carolina State University announced another allotropic development they call Q-carbon, created by high-energy, low-power pulses in amorphous carbon dust. Q-carbon is reported to indicate ferromagetism, fluorescence, and hardness that is superior to diamonds.
Genesis
Carbon is the fourth most abundant chemical element in the universe that can be observed by mass after hydrogen, helium, and oxygen. Carbon is abundant in the Sun, stars, comets, and in the atmosphere of most planets. Some meteorites contain microscopic diamonds formed when the solar system is still a protoplanet disk. Microscopic diamonds can also be formed by strong pressure and high temperature at the site of meteorite impact.
In 2014 NASA announced a highly upgraded database for tracking polycyclic aromatic hydrocarbons (PAHs) in the universe. More than 20% of the carbon in the universe may be associated with PAHs, carbon and hydrogen complexes without oxygen. These compounds illustrate the PAH world hypothesis in which they are hypothesized to have a role in abiogenesis and the formation of life. PAHs appear to have formed "several billion years" after the Big Bang, are widespread throughout the universe, and are associated with new stars and extrasolar planets.
It is estimated that solid earth as a whole contains 730 ppm of carbon, with 2,000 ppm in the nucleus and 120 ppm in combined coatings and crusts. Since the mass of the earth is 5,972 ÃÆ' - 10 Ã, kg , this would imply 4360 million gigantic carbon. This is much more than the amount of carbon in the oceans or atmospheres (below).
In combination with oxygen in carbon dioxide, carbon is found in Earth's atmosphere (about 810 gigatons of carbon) and dissolves in all bodies of water (about 36,000 gigatons of carbon). Approximately 1,900 gigatons of carbon are present in the biosphere. Hydrocarbons (such as coal, petroleum, and natural gas) contain carbon as well. Coal "reserves" (not "resources") amount to about 900 gigatons with perhaps 18,000 Gt of resources. Oil reserves are about 150 gigatons. The proven natural gas source is 175 ÃÆ' - 10 12 cubic meter (contains about 105 gigatons of carbon), but the study estimates the other 900 ÃÆ' - 10 12 cubic meter of "unconventional" deposits such as shale gas, representing about 540 gigatons of carbon.
Carbon is also found in methane hydrates in the polar regions and under the sea. Various estimates place this carbon between 500, 2500 Gt, or 3,000 Gt.
In the past, the amount of hydrocarbons was greater. According to one source, in the period 1751 to 2008 about 347 gigaton carbon was released as carbon dioxide into the atmosphere from the burning of fossil fuels. Another source puts an amount added to the atmosphere for the period from 1750 to 879 Gt, and the total goes to the atmosphere, the sea, and the soil (like peat bogs) at nearly 2,000 Gt.
Carbon is a constituent (about 12% mass) of the mass of very large carbonate rock (limestone, dolomite, marble and so on). Highly carbon-rich coal (anthracite contains 92-98%) and is the largest commercial source of carbon minerals, accounting for 4,000 gigatons or 80% of fossil fuels.
As for the individual carbon allotropes, graphite is found in large numbers in the United States (mostly in New York and Texas), Russia, Mexico, Greenland, and India. Natural diamonds occur in stone kimberlite, found in the ancient "neck" of volcanoes, or "pipes". Most diamond deposits exist in Africa, especially in South Africa, Namibia, Botswana, the Republic of Congo, and Sierra Leone. Diamond deposits have also been found in Arkansas, Canada, the Russian Arctic, Brazil, and in Northern and Western Australia. Diamonds are now recovering from the seabed at the Cape of Good Hope. Diamonds are found naturally, but about 30% of all industrial diamonds used in the US are now manufactured.
Carbon-14 forms in the upper layers of the troposphere and the stratosphere at altitudes of 9-15 km by reactions precipitated by cosmic rays. Thermal neutrons are produced that collide with nitrogen-14 cores, forming carbon-14 and protons. Thus, 1.5% ÃÆ' - 10 -10 of atmospheric carbon dioxide contains carbon-14.
Carbon-rich asteroids are relatively more dominant on the outside of the asteroid belt in our solar system. This asteroid has not been directly sampled by scientists. Asteroids can be used in hypothetical space-based carbon mining, which may be possible in the future, but currently technologically impossible.
Isotope
The carbon isotope is an atomic nucleus containing six protons plus a number of neutrons (varies from 2 to 16). Carbon has two stable and natural isotopes. The carbon-12 isotope ( 12 C) forms 98.93% of the Earth's carbon, while carbon-13 ( 13 C) makes up 1.07% of the rest. The concentration of 12 C was further enhanced in biological materials because of biochemical reactions discriminating 13 C. In 1961, the International Union of Pure and Applied Chemistry (IUPAC) adopted the carbon-12 isotope as base for atomic weights. Carbon identification in a nuclear magnetic resonance experiment (NMR) was performed with 13 C. isotope
Carbon-14 ( 14 C) is a naturally occurring radioisotope, made in the upper atmosphere (lower stratosphere and upper troposphere) by nitrogen interactions with cosmic rays. It is found in trace amounts on Earth 1 part per trillion (0.00000001%) or more, mostly limited to the atmosphere and shallow deposits, especially peat and other organic materials. This isotope decays with 0.158 MeV? - emissions. Because of its relatively short half-life of 5730 years, 14 C is almost nonexistent in ancient rocks. The amount of 14 C in the atmosphere and living organisms is almost constant, but decreases predictably in their bodies after death. This principle is used in radiocarbon dating, which was discovered in 1949, which has been used extensively to determine the age of carbon materials by age up to about 40,000 years.
There are 15 known and short-lived carbon isotopes that are 8 C that decay through proton emissions and alpha decay and have a half-life of 1,98739x10 -21 s. The exotic 19 C exhibits halo nuclear, which means its fingers are big enough than expected if the core is a constant density ball.
Formation in stars
The formation of nuclei of carbon atoms occurs in giant stars or supergiant through a triple-alpha process. This requires almost simultaneous collisions of three alpha particles (helium nuclei), as a further nuclear fusion reaction product of helium with hydrogen or other helium cores producing lithium-5 and beryllium-8, both highly unstable and decaying almost directly back into smaller core. The triple-alpha process occurs in temperatures over 100 megakelvin and helium concentrations that rapid expansion and cooling of the early universe are prohibited, and therefore no significant carbon was created during the Big Bang.
According to current physical cosmology theory, carbon forms in the star's interior on a horizontal branch. When a massive star dies as a supernova, carbon is dispersed into space as dust. This dust becomes the component material for the formation of next-generation star systems with increasing planets. The Solar System is one such star system with carbon abundance, enabling life as we know it.
The CNO cycle is an additional hydrogen fusion mechanism that moves stars, where carbon operates as a catalyst.
The transition rotation of various forms of carbon monoxide isotopes (eg, 12 CO, 13 CO, and 18 CO) are detected in submillimeter wavelength range, and used in the study of newly formed stars in molecular clouds.
Carbon cycle
In terrestrial conditions, converting one element to another is very rare. Therefore, the amount of carbon in the Earth is effectively constant. Thus, a process using carbon should get it from somewhere and dispose of it elsewhere. The carbon path in the environment forms a carbon cycle. For example, the photosynthetic plant draws carbon dioxide from the atmosphere (or seawater) and builds it into biomass, as in the Calvin cycle, a process of carbon fixation. Some of this biomass is eaten by animals, while some carbon is exhaled by animals as carbon dioxide. The carbon cycle is much more complicated than this short loop; for example, some carbon dioxide dissolved in the oceans; if bacteria do not consume them, dead plants or animals can become petroleum or coal, which releases carbon when it is burned.
Maps Carbon
​​Compound
Organic compound
Carbon can form a very long chain of carbon-carbon interconnect bonds, a property called catenation. The bonds of carbon-carbon are strong and stable. Through catenation, carbon forms countless compounds. The calculation of unique compounds shows that it contains more carbon than does not. Similar claims can be made for hydrogen because most organic compounds also contain hydrogen.
The simplest form of organic molecule is a hydrocarbon - a large group of organic molecules composed of hydrogen atoms bound to a chain of carbon atoms. Long chains, side chains and functional groups all affect the properties of organic molecules.
Carbon occurs in all known organic life and is the basis of organic chemistry. When combined with hydrogen, it forms various hydrocarbons important to the industry as coolants, lubricants, solvents, as chemical feedstocks for the manufacture of plastics and petrochemicals, and as fossil fuels.
When combined with oxygen and hydrogen, carbon can form many groups of important biological compounds including sugar, lignans, chitin, alcohols, fats, and aromatic, carotenoid and terpene esters. With nitrogen to form alkaloids, and with the addition of sulfur also forms antibiotics, amino acids, and rubber products. With the addition of phosphorus to these other elements, it forms DNA and RNA, the chemical code of life, and adenosine triphosphate (ATP), the most important energy transfer molecule in all living cells.
Inorganic compounds
The compounds which normally contain carbon associated with minerals or those that do not bond to other carbon atoms, halogen, or hydrogen, are treated separately from classical organic compounds; the definition is not rigid, and the classification of some compounds may vary from author to author (see reference article above). Among these are simple carbon oxides. The most prominent oxide is carbon dioxide (CO 2 ). It was once the main constituent of paleoatmosphere, but is a minor component of Earth's current atmosphere. Dissolved in water, form carbonic acid ( H
2 CO
3 ), but as most compounds with some single-binding oxygen on one carbon it is unstable. Through these intermediate, though, stable-resonance carbonate ions are produced. Some of the important minerals are carbonates, especially calcite. Carbon disulfide ( CS
2 ) similar. However, due to its physical properties and its relation to organic synthesis, carbon disulfide is sometimes classified as an organic solvent.
The other common oxide is carbon monoxide (CO). It is formed by incomplete combustion, and is a colorless and odorless gas. Each molecule contains triple bonds and is quite polar, resulting in a tendency to bind permanently to a hemoglobin molecule, replacing oxygen, which has a lower binding affinity. Cyanide (CN - ), has a similar structure, but behaves like a halide ion (pseudohalogen). For example, it can form a cyanogen nitride molecule ((CN) 2 ), similar to a diatomic halide. Similarly, the heavier analogues of cyanide, cyaphide (CP - ), are also considered inorganic, although the simplest derivatives are highly unstable. Other unusual oxides are carbon suboxide ( C
3 O
2 ), mono dicarbon that is not stable (C 2 O), carbon trioxide (CO 3 ), cyclopentanepentone (C 5 O 5 ), cyclohexanehexone (C 6 O 6 ), and mellitik anhydride (C 12 O 9 ). However, the mellican anhydride is the acyl of three mellitic acid anhydrides; In addition, it contains benzene rings. Thus, many chemists consider it organic.
With reactive metals, such as tungsten, carbon forms carbides (C 4 - ) or acetylides ( C 2 -
2 ) to form alloys with high melting point. This anion is also associated with methane and acetylene, both of which are very weak acids. With electronegativity 2.5, carbon prefers to form covalent bonds. Some carbides are covalent lattices, such as carborundum (SiC), which resemble diamonds. Nevertheless, even the most polar and salt-like carbides are not entirely ionic compounds.
Organometallic compound
The organometallic compound definitively contains at least one carbon-metal covalent bond. Various kinds of such compounds exist; The main classes include simple alkyl-metal compounds (eg, tetraethyllead) ,? 2 -alkena compounds (eg, Zeise's salt), and? 3 -common compounds (for example, allylpalladium chloride dimer); the metallocene contains a cyclopentadienyl ligand (eg, ferrocene); and complex metal carbene metals. Many carbonyls of metals and metal cyanides (eg, tetracarbonylnickel and potassium ferricyanide); some workers consider carbonyl and cyanide complexes without other carbon ligands to be purely inorganic, and not organometallic. However, most organometall chemists consider metal complexes with carbon ligands, even 'inorganic carbon' (for example, carbonyl, cyanide, and some carbide and acetylide) to become organometallic in nature. Complex metals containing organic ligands without carbon-metal covalent bonds (eg, carboxylates of metal) are referred to as metalorganic compounds.
While carbon is understood to be particularly fond of the formation of four covalent bonds, other exotic bonding schemes are also known. An interesting compound containing hexacoordinated ocacedral carbon has been reported. The cation of the compound is [(Ph 3 PAu) 6 C] 2 . This phenomenon has been attributed to the aurophilicity of the gold ligand, which provides additional stabilization of the labile species. In nature, the iron-molybdenum cofactor (FeMoco) responsible for the fixation of microbial nitrogen also has an octahedral carbon center (formally carbide, C (-IV)) bound to six iron atoms. By 2016, it is certain that, in line with previous theoretical predictions, the dation of hexamethylbenzene contains carbon atoms with six bonds, with the formulation of [MeC (? 5 -C 5 I < 5 )] 2 , making it an "organic metallocene". Thus, the MeC fragment 3 is bound to? 5 -C 5 Me 5 - fragment through all five carbon from the ring.
It is important to note that in the above cases, each bond to carbon contains less than two formal electron pairs, making them hypercoordinate, but not hypervalent. Even in the case of alleged 10-C-5 species (ie, carbon with five ligands and ten formal electrons), as reported by Akiba and co-workers, electronic structure calculations concluded that the total number of electrons around the carbon is still less than eight, in the case of other compounds described by the three center bonds.
History and etymology
The English name carbon comes from Latin carbo for coal and charcoal, from which also comes the French word charbon , which means charcoal. In Germany, the Netherlands and Denmark, the names for carbon are Kohlenstoff , koolstof and kulstof , all of which literally mean coal substance.
Carbon is found in prehistory and is known in the form of soot and char to the earliest human civilization. Diamonds are known to be possible in the early 2500 BC in China, while carbon in the form of charcoal was made around Roman times by the same chemical as it is today, by heating wood in clay-covered pyramids to exclude air.
In 1722, Renà © à © Antoine Ferchault de Rà © å © aumur shows that iron is converted into steel through the absorption of several substances, now known as carbon. In 1772, Antoine Lavoisier pointed out that diamonds are a form of carbon; when he burns charcoal and diamond samples and finds that it does not produce water and both release the same amount of carbon dioxide per gram. In 1779, Carl Wilhelm Scheele pointed out that graphite, which has been considered a tin form, is identical to charcoal but with a mixture of small iron, and it gives "air acid" (its name for carbon dioxide) when oxidized with nitric acid. In 1786, the French scientists Claude Louis Berthollet, Gaspard Monge and C. A. Vandermonde asserted that graphite mostly contains carbon by oxidizing oxygen in the same way as Lavoisier does with diamonds. Several more iron were abandoned, which according to French scientists needed for graphite structures. In their publication, they propose the name carbone (Latin carbonum ) for elements in graphite released as gases on burned graphite. Antoine Lavoisier then recorded carbon as an element in his 1789 textbook.
A new allotrope of carbon, fullerene, which was discovered in 1985 included nanostructured forms such as buckyballs and nanotubes. Their inventors - Robert Curl, Harold Kroto and Richard Smalley - received the Nobel Prize in Chemistry in 1996. New interest generated in the new form leads to the discovery of further exotic alotropes, including carbon glass, and the realization that "amorphous carbon" is not entirely amorphous.
Production
Graphite
Deposits of life-sustaining natural graphite occur in many parts of the world, but the most economically important sources are in China, India, Brazil, and North Korea. Graphite deposition is a metamorphic origin, found in association with quartz, mica and feldspars in schist, gneisses and metamorphic and limestone sandstones as lenses or veins, sometimes meters or more in thickness. The precipitated graphite in Borrowdale, Cumberland, England was initially of sufficient size and purity which, until the 19th century, pencils were made only by sawing natural blocks of graphite into strips before wrapping wooden pieces. Today, smaller graphite deposits are obtained by destroying the parent rock and floating the lighter graphite into water.
There are three types of natural graphite - amorphous flakes, flakes or crystals, and veins or bumps. Amorphous graphite is the lowest and most abundant quality. Contrary to science, in the "amorphous" industry it refers to a very small crystal size rather than a lack of crystal structure. Amorphous is used for lower value graphite products and is the lowest priced graphite. Large deposits of amorphous graphite are found in China, Europe, Mexico and the United States. Graphite flakes are less common and of higher quality than amorphous; it occurs as a separate plate that crystallizes in metamorphic rocks. Graphite flakes can quadruple amorphous prices. Good quality flakes can be processed into expandable graphite for many uses, such as flame retardants. The leading deposits are found in Austria, Brazil, Canada, China, Germany and Madagascar. Vein or graphite lumps are the rarest, most precious, and highest quality natural graphite. It occurs in the blood vessels along the intrusive contact in a solid lump, and it is only commercially mined in Sri Lanka.
According to USGS, world production of natural graphite is 1.1 million tons in 2010, where China accounts for 800,000 t, India 130,000 t, Brazil 76,000 t, North Korea 30,000 t and Canada 25,000 t. No natural graphite was reported mined in the United States, but 118,000 synthetic graphite tones with an estimated value of $ 998 million were produced in 2009.
Diamond
The diamond supply chain is controlled by a number of powerful businesses, and is also highly concentrated in a small number of locations around the world (see figure).
Only a small part of the diamond ore is made up of actual diamonds. The ore is destroyed, where care must be taken to prevent larger diamonds from being destroyed in this process and then the particles are sorted by density. Today, the diamond is located in the diamond-rich density fraction with the help of X-ray fluorescence, after which the final sorting step is done by hand. Before the use of X-rays became commonplace, the separation was done by belt grease; diamonds have a stronger tendency to stick to fats than other minerals in the ore.
Historically diamonds are known to be found only in alluvial deposits in southern India. India led the world in the production of diamonds since their discovery around the 9th century BC to the mid-18th century, but the commercial potential of these sources was exhausted at the end of the 18th century and at that time India was hindered by Brazil where diamond the first non-Indian was discovered in 1725.
The diamond production of the primary deposit (kimberlites and lamproites) only began in 1870 after the discovery of the Diamond field in South Africa. Production has increased over time and now the total accumulated 4.5 billion carats have been mined since that date. Approximately 20% of that amount has been mined in the last 5 years alone, and over the past ten years 9 new mines have started production while the other 4 are waiting to be opened soon. Most of these mines are located in Canada, Zimbabwe, Angola, and one in Russia.
In the United States, diamonds have been found in Arkansas, Colorado, and Montana. In 2004, the surprising discovery of microscopic diamonds in the United States led to massive kimberlite sampling in January 2008 in remote Montana.
Currently, most commercially tradable diamond deposits are located in Russia, Botswana, Australia, and the Democratic Republic of Congo. In 2005, Russia produced nearly a fifth of the global diamond output, reports the British Geological Survey. Australia has the richest diamantiferous pipeline with production reaching a peak of 42 metric tons (41 ton long, 46 ton short) per year in the 1990s. There are also commercial deposits actively mined in Canada's Northwest Territories, Siberia (mostly in Yakutia, for example, Mir pipes and Udachnaya pipelines), Brazil, and in Northern and Western Australia.
Apps
Carbon is essential to all known life systems, and without it life as we know it does not exist (see alternative biochemistry). The main economic uses of carbon other than food and wood are in the form of hydrocarbons, especially fossil methane and crude oil (petroleum). Crude oil is refined at the refinery by the petrochemical industry to produce gasoline, kerosene, and other products. Cellulose is a carbon-containing natural polymer produced by plants in the form of wood, cotton, linen, and hemp. Cellulose is used primarily to maintain structures in plants. Valuable commercial carbon polymers of animals include wool, cashmere and silk. Plastics are made of synthetic carbon polymers, often with oxygen and nitrogen atoms that are entered regularly in the major polymer chains. The raw material for many of these synthetic substances comes from crude oil.
The use of carbon and its compounds varies greatly. Can form alloys with iron, the most common is carbon steel. Graphite is combined with clay to form 'lead' used in pencils used for writing and drawing. It is also used as a lubricant and pigment, as a molding material in glass manufacture, in electrodes for dry batteries and electroplating and electroforming, in brushes for electric motors and as a moderator of neutrons in nuclear reactors.
Charcoal is used as a drawing material in artwork, barbecue grills, iron smelting, and many other applications. Wood, coal and oil are used as fuel for energy production and heating. Gems of gem quality are used in jewelry, and industrial diamonds are used in drilling, cutting and polishing equipment for metal and stone machining. Plastics are made of hydrocarbon fossils, and carbon fibers, made with synthetic polyester fiber pyrolysis used to reinforce plastics to form advanced, lightweight composite materials.
Carbon fibers are made with filamentous pyrolysis extruded and stretched from polyacrylonitrile (PAN) and other organic substances. The crystallographic structure and mechanical properties of the fibers depend on the type of starting material, and on subsequent processing. The carbon fiber made of PAN has a structure resembling a narrow graphite filament, but the heat processing can rearrange the structure into a continuous rolled sheet. The result is a fiber with a special tensile strength higher than steel.
Carbon black is used as a black pigment in printing ink, artist oil paint and water color, carbon paper, automotive finish coating, Indian ink and laser printer toner. Carbon black is also used as a filler in rubber products such as tires and plastic compounds. Activated charcoal is used as an adsorbent and adsorbent in a filter material in various applications such as gas masks, water purification, and extractor kitchen hoods, and in medicine to absorb toxins, toxins, or gases from the digestive system. Carbon is used in chemical reduction at high temperatures. Cokes are used to reduce iron ore to iron (smelting). The case of steel hardening is achieved by heating the finished steel components in carbon powder. Silicone carbide, tungsten, boron and titanium, is one of the most difficult materials known, and is used as abrasive in cutting and grinding. Carbon compounds make up most of the materials used in clothing, such as textiles and natural and synthetic leather, and almost all interior surfaces in built environments other than glass, stone and metal.
Diamonds
The diamond industry is divided into two categories: one dealing with grade gem diamonds and the other, with industrial grade diamonds. While large trades in both types of diamonds exist, both markets act dramatically differently.
Unlike precious metals such as gold or platinum, gem gems do not trade as commodities: there is a substantial mark up in diamond sales, and there is no very active market for resale diamonds.
Industrial diamonds are highly valued for their hardness and thermal conductivity, with the quality of clarity of clarity and color being largely irrelevant. About 80% of mined diamonds (equal to about 100 million carats or 20 tons per year) are unsuitable for use because gemstones are degraded for industrial use (known as bort) . synthetic diamonds, invented in 1950, invented almost instantaneous industrial applications; 3 billion diamonds (600 tons) of synthetic diamonds are produced each year.
The dominant use of the diamond industry is cutting, drilling, grinding, and polishing. Most of these applications do not require large diamonds; In fact, most gem-quality gems except for their small size can be used industrially. Diamonds are embedded in drill or chainsaw tips, or ground into powder for use in grinding and polishing applications. Specific applications include laboratory use as containment for high-pressure experiments (see diamond anvil cells), high-performance bearings, and limited use in special windows. With the continuous progress in the production of synthetic diamonds, new applications become feasible. Gathering a lot of excitement is the possible use of diamonds as semiconductors suitable for microchips, and because of their exceptional heat conductance properties, as heat sinks in electronics.
Precautions
Pure carbon has very low toxicity to humans and can be handled and even digested safely in the form of graphite or charcoal. It is resistant to dissolution or chemical attack, even in the acid content of the gastrointestinal tract. As a result, after entry into the body tissue will likely remain indefinitely. Carbon black is probably one of the first pigments used for tattoos, and ÃÆ'-tzi Iceman was found to have a carbon tattoo that survived during his life and for 5200 years after his death. Inhaling large amounts of coal or soot (carbon black) dust can be harmful, irritating lung tissue and causing congestive lung disease, mine worker pneumoconiosis. Diamond dust that is used as an abrasive material can be dangerous if ingested or inhaled. The carbon microparticles are produced in the exhaust fumes of diesel engines, and can accumulate in the lungs. In this example, damage can occur due to contaminants (eg, organic chemicals, heavy metals) rather than from the carbon itself.
Carbon generally has a low toxicity to life on Earth; but carbon nanoparticles are deadly to Drosophila.
Carbon can burn strongly and brightly in the presence of air at high temperatures. The large accumulation of coal, which remains inert for hundreds of millions of years in the absence of oxygen, can spontaneously burn when exposed to air at the ends of coal mine waste, storage of cargo ships and coal bunkers, as well as storage areas.
In a nuclear application where graphite is used as a neutron moderator, Wigner's energy accumulation is followed by a sudden spontaneous release. Annealing of at least 250 ° C can release energy safely, even in the wrong Windscale fire procedure, causing other reactor materials to burn.
Various carbon compounds include lethal toxins such as tetrodotoxin, rectin lectins from seeds of Ricinus communis, cyanide (CN - ), and carbon monoxide; and important things like living as glucose and protein.
The bond to carbon
See also
- Carbon chauvinism
- Carbon Determination
- Carbon footprint
- Carbon star
- Low carbon economy
- Timeline of carbon nanotubes
References
Bibliography
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemical Elements (2nd ed.). Butterworth-Heinemann. ISBN: 0-08-037941-9.
External links
- Carbon on In Our Time on the BBC.
- Carbon in Periodic Video Table (University of Nottingham)
- Carbon in Britannica
- Extensive Carbon Page in asu.edu
- The use of electrochemical carbon
- Carbon - Super Goods. Animation with 3D sound and interactive models.
Source of the article : Wikipedia
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