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102-422: CFC-13—like all chlorofluorocarbon compounds—contains atoms of carbon (C), chlorine (Cl), and fluorine (F). It can be prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride : This reaction can also produce trichlorofluoromethane (CCl 3 F), dichlorodifluoromethane (CCl 2 F 2 ) and tetrafluoromethane (CF 4 ). Following

204-730: A hexagonal crystal lattice with all atoms covalently bonded and properties similar to those of diamond. Fullerenes are a synthetic crystalline formation with a graphite-like structure, but in place of flat hexagonal cells only, some of the cells of which fullerenes are formed may be pentagons, nonplanar hexagons, or even heptagons of carbon atoms. The sheets are thus warped into spheres, ellipses, or cylinders. The properties of fullerenes (split into buckyballs, buckytubes, and nanobuds) have not yet been fully analyzed and represent an intense area of research in nanomaterials . The names fullerene and buckyball are given after Richard Buckminster Fuller , popularizer of geodesic domes , which resemble

306-706: A nuclear halo , which means its radius is appreciably larger than would be expected if the nucleus were a sphere of constant density. Formation of the carbon atomic nucleus occurs within a giant or supergiant star through the triple-alpha process . This requires a nearly simultaneous collision of three alpha particles (helium nuclei), as the products of further nuclear fusion reactions of helium with hydrogen or another helium nucleus produce lithium-5 and beryllium-8 respectively, both of which are highly unstable and decay almost instantly back into smaller nuclei. The triple-alpha process happens in conditions of temperatures over 100 megakelvins and helium concentration that

408-578: A semiconductor suitable to build microchips from, or the use of diamond as a heat sink in electronics . Significant research efforts in Japan , Europe , and the United States are under way to capitalize on the potential offered by diamond's unique material properties, combined with increased quality and quantity of supply starting to become available from synthetic diamond manufacturers. Graphite , named by Abraham Gottlob Werner in 1789, from

510-434: A π-cloud , graphite conducts electricity , but only in the plane of each covalently bonded sheet. This results in a lower bulk electrical conductivity for carbon than for most metals. The delocalization also accounts for the energetic stability of graphite over diamond at room temperature. At very high pressures, carbon forms the more compact allotrope, diamond, having nearly twice the density of graphite. Here, each atom

612-549: A C-C bond length of 154  pm . This network of unstrained covalent bonds makes diamond extremely strong. Diamond is thermodynamically less stable than graphite at pressures below 1.7  GPa . The dominant industrial use of diamond is cutting , drilling ( drill bits ), grinding (diamond edged cutters), and polishing. Most uses of diamonds in these technologies do not require large diamonds, and most diamonds that are not gem-quality can find an industrial use. Diamonds are embedded in drill tips and saw blades or ground into

714-418: A carbon atom with six bonds. More specifically, the dication could be described structurally by the formulation [MeC(η -C 5 Me 5 )] , making it an "organic metallocene " in which a MeC fragment is bonded to a η -C 5 Me 5 fragment through all five of the carbons of the ring. It is important to note that in the cases above, each of the bonds to carbon contain less than two formal electron pairs. Thus,

816-550: A carbon-metal covalent bond (e.g., metal carboxylates) are termed metalorganic compounds. While carbon is understood to strongly prefer formation of four covalent bonds, other exotic bonding schemes are also known. Carboranes are highly stable dodecahedral derivatives of the [B 12 H 12 ] unit, with one BH replaced with a CH . Thus, the carbon is bonded to five boron atoms and one hydrogen atom. The cation [(Ph 3 PAu) 6 C] contains an octahedral carbon bound to six phosphine-gold fragments. This phenomenon has been attributed to

918-450: A component of some prosthetic devices. It was first produced by Bernard Redfern in the mid-1950s at the laboratories of The Carborundum Company, Manchester, UK. He had set out to develop a polymer matrix to mirror a diamond structure and discovered a resole (phenolic) resin that would, with special preparation, set without a catalyst. Using this resin, the first glassy carbon was produced. The preparation of glassy carbon involves subjecting

1020-462: A density of about 2 kg/m . Similarly, glassy carbon contains a high proportion of closed porosity , but contrary to normal graphite, the graphitic layers are not stacked like pages in a book, but have a more random arrangement. Linear acetylenic carbon has the chemical structure −(C≡C) n − . Carbon in this modification is linear with sp orbital hybridization , and is a polymer with alternating single and triple bonds. This carbyne

1122-518: A hardness superior to diamonds. In the vapor phase, some of the carbon is in the form of highly reactive diatomic carbon dicarbon ( C 2 ). When excited, this gas glows green. Carbon is the fourth most abundant chemical element in the observable universe by mass after hydrogen, helium, and oxygen. Carbon is abundant in the Sun, stars, comets, and in the atmospheres of most planets. Some meteorites contain microscopic diamonds that were formed when

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1224-413: A high activation energy barrier, the transition into graphite is so slow at normal temperature that it is unnoticeable. However, at very high temperatures diamond will turn into graphite, and diamonds can burn up in a house fire. The bottom left corner of the phase diagram for carbon has not been scrutinized experimentally. Although a computational study employing density functional theory methods reached

1326-425: A hydrogen based engine in cars. The amorphous form is an assortment of carbon atoms in a non-crystalline, irregular, glassy state, not held in a crystalline macrostructure. It is present as a powder, and is the main constituent of substances such as charcoal, lampblack (soot), and activated carbon . At normal pressures, carbon takes the form of graphite, in which each atom is bonded trigonally to three others in

1428-471: A loose three-dimensional web. Each cluster is about 6 nanometers wide and consists of about 4000 carbon atoms linked in graphite -like sheets that are given negative curvature by the inclusion of heptagons among the regular hexagonal pattern. This is the opposite of what happens in the case of buckminsterfullerenes , in which carbon sheets are given positive curvature by the inclusion of pentagons . The large-scale structure of carbon nanofoam

1530-435: A lower binding affinity. Cyanide (CN ), has a similar structure, but behaves much like a halide ion ( pseudohalogen ). For example, it can form the nitride cyanogen molecule ((CN) 2 ), similar to diatomic halides. Likewise, the heavier analog of cyanide, cyaphide (CP ), is also considered inorganic, though most simple derivatives are highly unstable. Other uncommon oxides are carbon suboxide ( C 3 O 2 ),

1632-482: A nanotube is cylindrical , with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several centimeters in length. There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Carbon nanobuds are

1734-477: A newly discovered allotrope of carbon in which fullerene like "buds" are covalently attached to the outer sidewalls of the carbon nanotubes . This hybrid material has useful properties of both fullerenes and carbon nanotubes. For instance, they have been found to be exceptionally good field emitters . Schwarzites are negatively curved carbon surfaces originally proposed by decorating triply periodic minimal surfaces with carbon atoms. The geometric topology of

1836-414: A plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons . The resulting network is 2-dimensional, and the resulting flat sheets are stacked and loosely bonded through weak van der Waals forces . This gives graphite its softness and its cleaving properties (the sheets slip easily past one another). Because of the delocalization of one of the outer electrons of each atom to form

1938-490: A powder for use in grinding and polishing applications (due to its extraordinary hardness). Specialized applications include use in laboratories as containment for high pressure experiments (see diamond anvil ), high-performance bearings , and specialized windows of technical apparatuses. The market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of

2040-526: A small number of stabilized carbocations (three bonds, positive charge), radicals (three bonds, neutral), carbanions (three bonds, negative charge) and carbenes (two bonds, neutral), although these species are much more likely to be encountered as unstable, reactive intermediates. Carbon occurs in all known organic life and is the basis of organic chemistry . When united with hydrogen, it forms various hydrocarbons that are important to industry as refrigerants, lubricants, solvents, as chemical feedstock for

2142-437: A static press or using explosives. It can also be produced by the thermal decomposition of a polymer, poly(hydridocarbyne) , at atmospheric pressure, under inert gas atmosphere (e.g. argon, nitrogen), starting at temperature 110 °C (230 °F). Graphenylene is a single layer carbon material with biphenylene -like subunits as basis in its hexagonal lattice structure. It is also known as biphenylene-carbon. Carbophene

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2244-578: A team of scientists from Rice University and the University of Sussex, three of whom were awarded the 1996 Nobel Prize in Chemistry. They are named for the resemblance to the geodesic structures devised by Richard Buckminster "Bucky" Fuller . Fullerenes are positively curved molecules of varying sizes composed entirely of carbon, which take the form of a hollow sphere, ellipsoid, or tube (the C60 version has

2346-1018: A useful material in blood-contacting implants such as prosthetic heart valves . Graphite is the most stable allotrope of carbon. Contrary to popular belief, high-purity graphite does not readily burn, even at elevated temperatures. For this reason, it is used in nuclear reactors and for high-temperature crucibles for melting metals. At very high temperatures and pressures (roughly 2000 °C and 5 GPa), it can be transformed into diamond. Natural and crystalline graphites are not often used in pure form as structural materials due to their shear-planes, brittleness and inconsistent mechanical properties. In its pure glassy (isotropic) synthetic forms, pyrolytic graphite and carbon fiber graphite are extremely strong, heat-resistant (to 3000 °C) materials, used in reentry shields for missile nosecones, solid rocket engines, high temperature reactors , brake shoes and electric motor brushes . Intumescent or expandable graphites are used in fire seals, fitted around

2448-432: A vast number of compounds , with about two hundred million having been described and indexed; and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions. The allotropes of carbon include graphite , one of the softest known substances, and diamond , the hardest naturally occurring substance. It bonds readily with other small atoms, including other carbon atoms, and

2550-406: A wide variety of applications (e.g., nano-electronics, optics , materials applications, etc.). They exhibit extraordinary strength, unique electrical properties, and are efficient conductors of heat . Non-carbon nanotubes have also been synthesized. Carbon nanotubes are a members of the fullerene structural family, which also includes buckyballs . Whereas buckyballs are spherical in shape,

2652-408: Is a 2 dimensional covalent organic framework . 4-6 carbophene has been synthesized from 1-3-5 trihydroxybenzene . It consists of 4-carbon and 6-carbon rings in 1:1 ratio. The angles between the three σ-bonds of the orbitals are approximately 120°, 90°, and 150°. AA'-graphite is an allotrope of carbon similar to graphite, but where the layers are positioned differently to each other as compared to

2754-441: Is a two-dimensional sheet of carbon with the atoms arranged in a hexagonal lattice. As of 2009, graphene appears to be the strongest material ever tested. The process of separating it from graphite will require some further technological development before it is economical for industrial processes. If successful, graphene could be used in the construction of a space elevator . It could also be used to safely store hydrogen for use in

2856-870: Is accomplished using chlorine treatment, hydrothermal synthesis, or high-temperature selective metal desorption under vacuum. Depending on the synthesis method, carbide precursor, and reaction parameters, multiple carbon allotropes can be achieved, including endohedral particles composed of predominantly amorphous carbon, carbon nanotubes, epitaxial graphene, nanocrystalline diamond, onion-like carbon, and graphitic ribbons, barrels, and horns. These structures exhibit high porosity and specific surface areas, with highly tunable pore diameters, making them promising materials for supercapacitor-based energy storage, water filtration and capacitive desalinization, catalyst support, and cytokine removal. Other metastable carbon phases, some diamondlike, have been produced from reactions of SiC or CH3SiCl3 with CF4. A one-dimensional carbon polymer with

2958-439: Is almost constant, but decreases predictably in their bodies after death. This principle is used in radiocarbon dating , invented in 1949, which has been used extensively to determine the age of carbonaceous materials with ages up to about 40,000 years. There are 15 known isotopes of carbon and the shortest-lived of these is C which decays through proton emission and has a half-life of 3.5 × 10 s. The exotic C exhibits

3060-407: Is also found in methane hydrates in polar regions and under the seas. Various estimates put this carbon between 500, 2500, or 3,000 Gt. According to one source, in the period from 1751 to 2008 about 347 gigatonnes of carbon were released as carbon dioxide to the atmosphere from burning of fossil fuels. Another source puts the amount added to the atmosphere for the period since 1750 at 879 Gt, and

3162-403: Is an allotrope sometimes called " hexagonal diamond", formed from graphite present in meteorites upon their impact on the earth. The great heat and pressure of the impact transforms the graphite into a denser form similar to diamond but retaining graphite's hexagonal crystal lattice . "Hexagonal diamond" has also been synthesized in the laboratory, by compressing and heating graphite either in

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3264-415: Is at 10.8 ± 0.2 megapascals (106.6 ± 2.0 atm; 1,566 ± 29 psi) and 4,600 ± 300 K (4,330 ± 300 °C; 7,820 ± 540 °F), so it sublimes at about 3,900 K (3,630 °C; 6,560 °F). Graphite is much more reactive than diamond at standard conditions, despite being more thermodynamically stable, as its delocalised pi system

3366-594: Is bonded tetrahedrally to four others, forming a 3-dimensional network of puckered six-membered rings of atoms. Diamond has the same cubic structure as silicon and germanium , and because of the strength of the carbon-carbon bonds , it is the hardest naturally occurring substance measured by resistance to scratching . Contrary to the popular belief that "diamonds are forever" , they are thermodynamically unstable ( Δ f G ° (diamond, 298 K) = 2.9 kJ/mol ) under normal conditions (298 K, 10  Pa) and should theoretically transform into graphite. But due to

3468-406: Is capable of forming multiple stable covalent bonds with suitable multivalent atoms. Carbon is a component element in the large majority of all chemical compounds , with about two hundred million examples having been described in the published chemical literature. Carbon also has the highest sublimation point of all elements. At atmospheric pressure it has no melting point, as its triple point

3570-553: Is carbon dioxide (CO 2 ). This was once the principal constituent of the paleoatmosphere , but is a minor component of the Earth's atmosphere today. Dissolved in water, it forms carbonic acid ( H 2 CO 3 ), but as most compounds with multiple single-bonded oxygens on a single carbon it is unstable. Through this intermediate, though, resonance-stabilized carbonate ions are produced. Some important minerals are carbonates, notably calcite . Carbon disulfide ( CS 2 )

3672-663: Is dissolved in the oceans; if bacteria do not consume it, dead plant or animal matter may become petroleum or coal, which releases carbon when burned. Carbon can form very long chains of interconnecting carbon–carbon bonds , a property that is called catenation . Carbon-carbon bonds are strong and stable. Through catenation, carbon forms a countless number of compounds. A tally of unique compounds shows that more contain carbon than do not. A similar claim can be made for hydrogen because most organic compounds contain hydrogen chemically bonded to carbon or another common element like oxygen or nitrogen. The simplest form of an organic molecule

3774-801: Is found in large quantities in the United States (mostly in New York and Texas ), Russia, Mexico, Greenland, and India. Natural diamonds occur in the rock kimberlite , found in ancient volcanic "necks", or "pipes". Most diamond deposits are in Africa, notably in South Africa, Namibia, Botswana, the Republic of the Congo, and Sierra Leone. Diamond deposits have also been found in Arkansas , Canada,

3876-422: Is found in trace amounts on Earth of 1 part per trillion (0.0000000001%) or more, mostly confined to the atmosphere and superficial deposits, particularly of peat and other organic materials. This isotope decays by 0.158 MeV β emission . Because of its relatively short half-life of 5700 ± 30  years, C is virtually absent in ancient rocks. The amount of C in the atmosphere and in living organisms

3978-457: Is high— 1 ( CCl 3 F = 1)—it is categorized as a Class I in the IPCC's list of ozone-depleting substances. CFC-13's radiative efficiency is high which results in a high global warming potential (GWPs) of 13 900 GWP-100 yr that is "surpassed by very few other greenhouse gases." It is categorized as a Class I in the list of ozone-depleting Substances. Starting in the 2010s, despite a global ban on

4080-510: Is injected into the zeolite, where the carbon gathers on the pores' walls, creating the negative curve. Dissolving the zeolite leaves the carbon. A team generated structures by decorating the pores of a zeolite with carbon through a Monte Carlo method . Some of the resulting models resemble schwarzite-like structures. Glassy carbon or vitreous carbon is a class of non-graphitizing carbon widely used as an electrode material in electrochemistry , as well as for high-temperature crucibles and as

4182-462: Is much more vulnerable to attack. For example, graphite can be oxidised by hot concentrated nitric acid at standard conditions to mellitic acid , C 6 (CO 2 H) 6 , which preserves the hexagonal units of graphite while breaking up the larger structure. Carbon sublimes in a carbon arc, which has a temperature of about 5800 K (5,530 °C or 9,980 °F). Thus, irrespective of its allotropic form, carbon remains solid at higher temperatures than

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4284-567: Is no long-range pattern of atomic positions. While entirely amorphous carbon can be produced, most amorphous carbon contains microscopic crystals of graphite -like, or even diamond -like carbon. Coal and soot or carbon black are informally called amorphous carbon. However, they are products of pyrolysis (the process of decomposing a substance by the action of heat), which does not produce true amorphous carbon under normal conditions. The buckminsterfullerenes , or usually just fullerenes or buckyballs for short, were discovered in 1985 by

4386-506: Is of considerable interest to nanotechnology as its Young's modulus is 40 times that of the hardest known material – diamond. In 2015, a team at the North Carolina State University announced the development of another allotrope they have dubbed Q-carbon , created by a high-energy low-duration laser pulse on amorphous carbon dust. Q-carbon is reported to exhibit ferromagnetism, fluorescence , and

4488-553: Is often detected via spectroscopy in extraterrestrial bodies, including comets and certain stars . Diamond is a well-known allotrope of carbon. The hardness , extremely high refractive index , and high dispersion of light make diamond useful for industrial applications and for jewelry. Diamond is the hardest known natural mineral . This makes it an excellent abrasive and makes it hold polish and luster extremely well. No known naturally occurring substance can cut or scratch diamond, except another diamond. In diamond form, carbon

4590-479: Is one of the costliest elements. The crystal structure of diamond is a face-centered cubic lattice having eight atoms per unit cell to form a diamond cubic structure. Each carbon atom is covalently bonded to four other carbons in a tetrahedral geometry . These tetrahedrons together form a 3-dimensional network of six-membered carbon rings in the chair conformation , allowing for zero bond angle strain. The bonding occurs through sp hybridized orbitals to give

4692-577: Is one such star system with an abundance of carbon, enabling the existence of life as we know it. It is the opinion of most scholars that all the carbon in the Solar System and the Milky Way comes from dying stars. The CNO cycle is an additional hydrogen fusion mechanism that powers stars, wherein carbon operates as a catalyst. Rotational transitions of various isotopic forms of carbon monoxide (for example, CO, CO, and CO) are detectable in

4794-561: Is reduced to a powder by a mixture of concentrated sulfuric and nitric acids at room temperature, glassy carbon is unaffected by such treatment, even after several months. Carbon nanofoam is the fifth known allotrope of carbon, discovered in 1997 by Andrei V. Rode and co-workers at the Australian National University in Canberra . It consists of a low-density cluster-assembly of carbon atoms strung together in

4896-503: Is similar to that of an aerogel , but with 1% of the density of previously produced carbon aerogels – only a few times the density of air at sea level . Unlike carbon aerogels, carbon nanofoam is a poor electrical conductor . Carbide-derived carbon (CDC) is a family of carbon materials with different surface geometries and carbon ordering that are produced via selective removal of metals from metal carbide precursors, such as TiC, SiC, Ti 3 AlC 2 , Mo 2 C , etc. This synthesis

4998-453: Is similar. Nevertheless, due to its physical properties and its association with 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, odorless gas. The molecules each contain a triple bond and are fairly polar , resulting in a tendency to bind permanently to hemoglobin molecules, displacing oxygen, which has

5100-566: Is stabilized in various multi-atomic structures with diverse molecular configurations called allotropes . The three relatively well-known allotropes of carbon are amorphous carbon , graphite , and diamond. Once considered exotic, fullerenes are nowadays commonly synthesized and used in research; they include buckyballs , carbon nanotubes , carbon nanobuds and nanofibers . Several other exotic allotropes have also been discovered, such as lonsdaleite , glassy carbon , carbon nanofoam and linear acetylenic carbon (carbyne). Graphene

5202-681: Is the hydrocarbon—a large family of organic molecules that are composed of hydrogen atoms bonded to a chain of carbon atoms. A hydrocarbon backbone can be substituted by other atoms, known as heteroatoms . Common heteroatoms that appear in organic compounds include oxygen, nitrogen, sulfur, phosphorus, and the nonradioactive halogens, as well as the metals lithium and magnesium. Organic compounds containing bonds to metal are known as organometallic compounds ( see below ). Certain groupings of atoms, often including heteroatoms, recur in large numbers of organic compounds. These collections, known as functional groups , confer common reactivity patterns and allow for

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5304-493: The International Union of Pure and Applied Chemistry (IUPAC) adopted the isotope carbon-12 as the basis for atomic weights . Identification of carbon in nuclear magnetic resonance (NMR) experiments is done with the isotope C. Carbon-14 ( C) is a naturally occurring radioisotope , created in the upper atmosphere (lower stratosphere and upper troposphere ) by interaction of nitrogen with cosmic rays. It

5406-512: The PAH world hypothesis where they are hypothesized to have a role in abiogenesis and formation of life. PAHs seem to have been formed "a couple of billion years" after the Big Bang , are widespread throughout the universe, and are associated with new stars and exoplanets . It has been estimated that the solid earth as a whole contains 730 ppm of carbon, with 2000 ppm in the core and 120 ppm in

5508-425: The aurophilicity of the gold ligands, which provide additional stabilization of an otherwise labile species. In nature, the iron-molybdenum cofactor ( FeMoco ) responsible for microbial nitrogen fixation likewise has an octahedral carbon center (formally a carbide, C(-IV)) bonded to six iron atoms. In 2016, it was confirmed that, in line with earlier theoretical predictions, the hexamethylbenzene dication contains

5610-695: The biosphere has been estimated at 550 gigatonnes but with a large uncertainty, due mostly to a huge uncertainty in the amount of terrestrial deep subsurface bacteria . Hydrocarbons (such as coal, petroleum, and natural gas) contain carbon as well. Coal "reserves" (not "resources") amount to around 900 gigatonnes with perhaps 18,000 Gt of resources. Oil reserves are around 150 gigatonnes. Proven sources of natural gas are about 175 × 10  cubic metres (containing about 105 gigatonnes of carbon), but studies estimate another 900 × 10  cubic metres of "unconventional" deposits such as shale gas , representing about 540 gigatonnes of carbon. Carbon

5712-455: The carbon cycle . For example, photosynthetic plants draw carbon dioxide from the atmosphere (or seawater) and build 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 considerably more complicated than this short loop; for example, some carbon dioxide

5814-428: The gemological characteristics of diamond, including clarity and color, mostly irrelevant. This helps explain why 80% of mined diamonds (equal to about 100 million carats or 20  tonnes annually) are unsuitable for use as gemstones and known as bort , are destined for industrial use. In addition to mined diamonds, synthetic diamonds found industrial applications almost immediately after their invention in

5916-405: The heat of formation of carbon compounds. Graphite conducts electricity , due to delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so are able to conduct electricity. However, the electricity is only conducted along the plane of the layers. In diamond, all four outer electrons of each carbon atom are 'localized' between

6018-616: The periodic table . Carbon makes up about 0.025 percent of Earth's crust. Three isotopes occur naturally, C and C being stable, while C is a radionuclide , decaying with a half-life of 5,700 years. Carbon is one of the few elements known since antiquity . Carbon is the 15th most abundant element in the Earth's crust , and the fourth most abundant element in the universe by mass after hydrogen , helium , and oxygen . Carbon's abundance, its unique diversity of organic compounds , and its unusual ability to form polymers at

6120-399: The submillimeter wavelength range, and are used in the study of newly forming stars in molecular clouds . Under terrestrial conditions, conversion of one element to another is very rare. Therefore, the amount of carbon on Earth is effectively constant. Thus, processes that use carbon must obtain it from somewhere and dispose of it somewhere else. The paths of carbon in the environment form

6222-403: The 1950s; another 400 million carats (80 tonnes) of synthetic diamonds are produced annually for industrial use, which is nearly four times the mass of natural diamonds mined over the same period. With the continuing advances being made in the production of synthetic diamond, future applications are beginning to become feasible. Garnering much excitement is the possible use of diamond as

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6324-459: The Greek γράφειν ( graphein , "to draw/write", for its use in pencils) is one of the most common allotropes of carbon. Unlike diamond, graphite is an electrical conductor. Thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under standard conditions , graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the standard state for defining

6426-989: The Latin carbo for coal and charcoal, whence also comes the French charbon , meaning charcoal. In German, Dutch and Danish, the names for carbon are Kohlenstoff , koolstof , and kulstof respectively, all literally meaning coal-substance. Allotropes of carbon Carbon is capable of forming many allotropes (structurally different forms of the same element) due to its valency ( tetravalent ). Well-known forms of carbon include diamond and graphite . In recent decades, many more allotropes have been discovered and researched, including ball shapes such as buckminsterfullerene and sheets such as graphene . Larger-scale structures of carbon include nanotubes , nanobuds and nanoribbons . Other unusual forms of carbon exist at very high temperatures or extreme pressures. Around 500 hypothetical 3‑periodic allotropes of carbon are known at

6528-645: The Russian Arctic, Brazil, and in Northern and Western Australia. Diamonds are now also being recovered from the ocean floor off the Cape of Good Hope . Diamonds are found naturally, but about 30% of all industrial diamonds used in the U.S. are now manufactured. Carbon-14 is formed in upper layers of the troposphere and the stratosphere at altitudes of 9–15 km by a reaction that is precipitated by cosmic rays . Thermal neutrons are produced that collide with

6630-459: The Solar System was still a protoplanetary disk . Microscopic diamonds may also be formed by the intense pressure and high temperature at the sites of meteorite impacts. In 2014 NASA announced a greatly 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, complex compounds of carbon and hydrogen without oxygen. These compounds figure in

6732-503: The addition of phosphorus to these other elements, it forms DNA and RNA , the chemical-code carriers of life, and adenosine triphosphate (ATP), the most important energy-transfer molecule in all living cells. Norman Horowitz , head of the Mariner and Viking missions to Mars (1965–1976), considered that the unique characteristics of carbon made it unlikely that any other element could replace carbon, even on another planet, to generate

6834-458: The allotropic form. For example, graphite is opaque and black, while diamond is highly transparent . Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known. Graphite is a good electrical conductor while diamond has a low electrical conductivity . Under normal conditions, diamond, carbon nanotubes , and graphene have

6936-445: The atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout

7038-451: The biochemistry necessary for life. Commonly carbon-containing compounds which are associated with minerals or which do not contain bonds to the other carbon atoms, halogens, or hydrogen, are treated separately from classical organic compounds; the definition is not rigid, and the classification of some compounds can vary from author to author (see reference articles above). Among these are the simple oxides of carbon. The most prominent oxide

7140-529: The carbon is bonded to. In general, covalent radius decreases with lower coordination number and higher bond order. Carbon-based compounds form the basis of all known life on Earth, and the carbon-nitrogen-oxygen cycle provides a small portion of the energy produced by the Sun, and most of the energy in larger stars (e.g. Sirius ). Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions. At standard temperature and pressure, it resists all but

7242-406: The coal-gas reaction used in coal gasification : Carbon combines with some metals at high temperatures to form metallic carbides, such as the iron carbide cementite in steel and tungsten carbide , widely used as an abrasive and for making hard tips for cutting tools. The system of carbon allotropes spans a range of extremes: Atomic carbon is a very short-lived species and, therefore, carbon

7344-489: The combined mantle and crust. Since the mass of the earth is 5.972 × 10  kg , this would imply 4360 million gigatonnes of carbon. This is much more than the amount of carbon in the oceans or atmosphere (below). In combination with oxygen in carbon dioxide, carbon is found in the Earth's atmosphere (approximately 900 gigatonnes of carbon — each ppm corresponds to 2.13 Gt) and dissolved in all water bodies (approximately 36,000 gigatonnes of carbon). Carbon in

7446-453: The conclusion that as T → 0 K and p → 0 Pa , diamond becomes more stable than graphite by approximately 1.1 kJ/mol, more recent and definitive experimental and computational studies show that graphite is more stable than diamond for T < 400 K , without applied pressure, by 2.7 kJ/mol at T  = 0 K and 3.2 kJ/mol at T  = 298.15 K. Under some conditions, carbon crystallizes as lonsdaleite ,

7548-550: The drivers behind the increase in CFC-13 and CFC-112a emissions were not certain. The IPCC AR5 reported that CFC-13's Atmospheric lifetime was 640 years. Carbon Carbon (from Latin carbo  'coal') is a chemical element ; it has symbol C and atomic number 6. It is nonmetallic and tetravalent —meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of

7650-503: The formal electron count of these species does not exceed an octet. This makes them hypercoordinate but not hypervalent. Even in cases of alleged 10-C-5 species (that is, a carbon with five ligands and a formal electron count of ten), as reported by Akiba and co-workers, electronic structure calculations conclude that the electron population around carbon is still less than eight, as is true for other compounds featuring four-electron three-center bonding . The English name carbon comes from

7752-484: The future, but is currently technologically impossible. Isotopes of carbon are atomic nuclei that contain six protons plus a number of neutrons (varying from 2 to 16). Carbon has two stable, naturally occurring isotopes. The isotope carbon-12 ( C) forms 98.93% of the carbon on Earth, while carbon-13 ( C) forms the remaining 1.07%. The concentration of C is further increased in biological materials because biochemical reactions discriminate against C. In 1961,

7854-423: The heavier group-14 elements. The electronegativity of carbon is 2.5, significantly higher than the heavier group-14 elements (1.8–1.9), but close to most of the nearby nonmetals, as well as some of the second- and third-row transition metals . Carbon's covalent radii are normally taken as 77.2 pm (C−C), 66.7 pm (C=C) and 60.3 pm (C≡C), although these may vary depending on coordination number and what

7956-612: The hexagonal layers of carbon atoms in graphite. It is unaffected by ordinary solvents, dilute acids, or fused alkalis. However, chromic acid oxidizes it to carbon dioxide. A single layer of graphite is called graphene and has extraordinary electrical, thermal, and physical properties. It can be produced by epitaxy on an insulating or conducting substrate or by mechanical exfoliation (repeated peeling) from graphite. Its applications may include replacing silicon in high-performance electronic devices. With two layers stacked, bilayer graphene results with different properties. Lonsdaleite

8058-675: The highest thermal conductivities 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 temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones , dolomites and carbon dioxide , but significant quantities occur in organic deposits of coal , peat , oil , and methane clathrates . Carbon forms

8160-509: The highest-melting-point metals such as tungsten or rhenium . Although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper, which are weaker reducing agents at room temperature. Carbon is the sixth element, with a ground-state electron configuration of 1s 2s 2p , of which the four outer electrons are valence electrons . Its first four ionisation energies, 1086.5, 2352.6, 4620.5 and 6222.7 kJ/mol, are much higher than those of

8262-414: 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 sugars, lignans , chitins , alcohols, fats, aromatic esters , carotenoids and terpenes . With nitrogen, it forms alkaloids , and with the addition of sulfur also it forms antibiotics, amino acids , and rubber products. With

8364-1053: The most polar and salt-like of carbides are not completely ionic compounds. Organometallic compounds by definition contain at least one carbon-metal covalent bond. A wide range of such compounds exist; major classes include simple alkyl-metal compounds (for example, tetraethyllead ), η -alkene compounds (for example, Zeise's salt ), and η -allyl compounds (for example, allylpalladium chloride dimer ); metallocenes containing cyclopentadienyl ligands (for example, ferrocene ); and transition metal carbene complexes . Many metal carbonyls and metal cyanides exist (for example, tetracarbonylnickel and potassium ferricyanide ); some workers consider metal carbonyl and cyanide complexes without other carbon ligands to be purely inorganic, and not organometallic. However, most organometallic chemists consider metal complexes with any carbon ligand, even 'inorganic carbon' (e.g., carbonyls, cyanides, and certain types of carbides and acetylides) to be organometallic in nature. Metal complexes containing organic ligands without

8466-408: The nuclei of nitrogen-14, forming carbon-14 and a proton. As such, 1.5% × 10 of atmospheric carbon dioxide contains carbon-14. Carbon-rich asteroids are relatively preponderant in the outer parts of the asteroid belt in the Solar System. These asteroids have not yet been directly sampled by scientists. The asteroids can be used in hypothetical space-based carbon mining , which may be possible in

8568-533: The order in graphite. Diamane is a 2D form of diamond. It can be made via high pressures, but without that pressure, the material reverts to graphene. Another technique is to add hydrogen atoms, but those bonds are weak. Using fluorine (xenon-difluoride) instead brings the layers closer together, strengthening the bonds. This is called f-diamane. Amorphous carbon is the name used for carbon that does not have any crystalline structure. As with all glassy materials, some short-range order can be observed, but there

8670-488: The organic precursors to a series of heat treatments at temperatures up to 3000 °C. Unlike many non-graphitizing carbons, they are impermeable to gases and are chemically extremely inert, especially those prepared at very high temperatures. It has been demonstrated that the rates of oxidation of certain glassy carbons in oxygen, carbon dioxide or water vapor are lower than those of any other carbon. They are also highly resistant to attack by acids. Thus, while normal graphite

8772-423: The outer wall of a nanotube) that combine the properties of both in a single structure. Of the other discovered allotropes, carbon nanofoam is a ferromagnetic allotrope discovered in 1997. It consists of a low-density cluster-assembly of carbon atoms strung together in a loose three-dimensional web, in which the atoms are bonded trigonally in six- and seven-membered rings. It is among the lightest known solids, with

8874-414: The perimeter of a fire door. During a fire the graphite intumesces (expands and chars) to resist fire penetration and prevent the spread of fumes. A typical start expansion temperature (SET) is between 150 and 300 °C. Graphite's specific gravity is 2.3, which makes it less dense than diamond. Graphite is slightly more reactive than diamond. This is because the reactants are able to penetrate between

8976-464: The plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct electricity in a direction at right angles to the plane. Graphite powder is used as a dry lubricant . Although it might be thought that this industrially important property is due entirely to the loose interlamellar coupling between sheets in the structure, in fact in a vacuum environment (such as in technologies for use in space ), graphite

9078-522: The present time, according to the Samara Carbon Allotrope Database (SACADA). Under certain conditions, carbon can be found in its atomic form. It can be formed by vaporizing graphite, by passing large electric currents to form a carbon arc under very low pressure. It is extremely reactive, but it is an intermediate product used in the creation of carbenes . Diatomic carbon can also be found under certain conditions. It

9180-507: The production of CFCs, five of these ozone-damaging emissions were on the rise. The atmospheric abundance of CFC-13 rose from 3.0 parts per trillion (ppt) in year 2010 to 3.3 ppt in year 2020 based on analysis of air samples gathered from sites around the world. Contrary to the Montreal Protocol, the atmospheric emissions of CFC-13 and four other chlorofluorocarbons (CFCs), increased between 2010 and 2020. As of 2023,

9282-526: The rapid expansion and cooling of the early universe prohibited, and therefore no significant carbon was created during the Big Bang. According to current physical cosmology theory, carbon is formed in the interiors of stars on the horizontal branch . When massive stars die as supernova, the carbon is scattered into space as dust. This dust becomes component material for the formation of the next-generation star systems with accreted planets. The Solar System

9384-561: The same form as a traditional stitched soccer ball). As of the early twenty-first century, the chemical and physical properties of fullerenes are still under heavy study, in both pure and applied research labs. In April 2003, fullerenes were under study for potential medicinal use — binding specific antibiotics to the structure to target resistant bacteria and even target certain cancer cells such as melanoma. Carbon nanotubes, also called buckytubes, are cylindrical carbon molecules with novel properties that make them potentially useful in

9486-470: The strongest oxidizers. It does not react with sulfuric acid , hydrochloric acid , chlorine or any alkalis . At elevated temperatures, carbon reacts with oxygen to form carbon oxides and will rob oxygen from metal oxides to leave the elemental metal. This exothermic reaction is used in the iron and steel industry to smelt iron and to control the carbon content of steel : Carbon reacts with sulfur to form carbon disulfide , and it reacts with steam in

9588-464: The structure is determined by the presence of ring defects, such as heptagons and octagons, to graphene 's hexagonal lattice. (Negative curvature bends surfaces outwards like a saddle rather than bending inwards like a sphere.) Recent work has proposed zeolite-templated carbons (ZTCs) may be schwarzites. The name, ZTC, derives from their origin inside the pores of zeolites , crystalline silicon dioxide minerals. A vapor of carbon-containing molecules

9690-509: The structure of fullerenes. The buckyballs are fairly large molecules formed completely of carbon bonded trigonally, forming spheroids (the best-known and simplest is the soccerball-shaped C 60 buckminsterfullerene ). Carbon nanotubes (buckytubes) 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 hybrid buckytube/buckyball materials (buckyballs are covalently bonded to

9792-416: The structure —(C≡C) n —. Its structure is relatively like that of Amorphous carbon. Cyclo[18]carbon (C 18 ) was synthesized in 2019. Many other allotropes have been hypothesized but have yet to be synthesized. The system of carbon allotropes spans an astounding range of extremes, considering that they are all merely structural formations of the same element. Between diamond and graphite: Despite

9894-414: The systematic study and categorization of organic compounds. Chain length, shape and functional groups all affect the properties of organic molecules. In most stable compounds of carbon (and nearly all stable organic compounds), carbon obeys the octet rule and is tetravalent , meaning that a carbon atom forms a total of four covalent bonds (which may include double and triple bonds). Exceptions include

9996-460: The temperatures commonly encountered on Earth, enables this element to serve as a common element of all known life . It is the second most abundant element in the human body by mass (about 18.5%) after oxygen. The atoms of carbon can bond together in diverse ways, resulting in various allotropes of carbon . Well-known allotropes include graphite , diamond , amorphous carbon , and fullerenes . The physical properties of carbon vary widely with

10098-458: The total going to the atmosphere, sea, and land (such as peat bogs ) at almost 2,000 Gt. Carbon is a constituent (about 12% by mass) of the very large masses of carbonate rock ( limestone , dolomite , marble , and others). Coal is very rich in carbon ( anthracite contains 92–98%) and is the largest commercial source of mineral carbon, accounting for 4,000 gigatonnes or 80% of fossil fuel . As for individual carbon allotropes, graphite

10200-529: The unanimous ratification of the 1987 Montreal Protocol —in response to concerns about the role of concentrations of chlorofluorocarbons (CFCs) in ozone layer -depletion in the stratosphere —a process was put into place to gradually phase out and replace CFC-13 and all the other CFCs. Research in the 1980s said that these man-made CFC compound compounds had opened a hole in ozone layer in the upper atmosphere or stratosphere that protects life on earth from UV radiation . CFC-13's ozone depletion potential (ODP)

10302-775: The unstable dicarbon monoxide (C 2 O), carbon trioxide (CO 3 ), cyclopentanepentone (C 5 O 5 ), cyclohexanehexone (C 6 O 6 ), and mellitic anhydride (C 12 O 9 ). However, mellitic anhydride is the triple acyl anhydride of mellitic acid; moreover, it contains a benzene ring. Thus, many chemists consider it to be organic. With reactive metals, such as tungsten , carbon forms either carbides (C ) or acetylides ( C 2 ) to form alloys with high melting points. These anions are also associated with methane and acetylene , both very weak acids. With an electronegativity of 2.5, carbon prefers to form covalent bonds . A few carbides are covalent lattices, like carborundum (SiC), which resembles diamond. Nevertheless, even

10404-477: Was found to be a very poor lubricant. This fact led to the discovery that graphite's lubricity is due to adsorbed air and water between the layers, unlike other layered dry lubricants such as molybdenum disulfide . Recent studies suggest that an effect called superlubricity can also account for this effect. When a large number of crystallographic defects (physical) bind these planes together, graphite loses its lubrication properties and becomes pyrolytic carbon ,

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