Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions. [82] 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. [113], In the United States, diamonds have been found in Arkansas, Colorado and Montana. Only a very small fraction of the diamond ore consists of actual diamonds. [79], Under terrestrial conditions, conversion of one element to another is very rare. [108], According to the USGS, world production of natural graphite was 1.1 million tonnes in 2010, to which China contributed 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 t of synthetic graphite with an estimated value of $998 million was produced in 2009.[108]. Most of these applications do not require large diamonds; in fact, most diamonds of gem-quality except for their small size can be used industrially. 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). Therefore, the amount of carbon on Earth is effectively constant. The amorphous form is an assortment of carbon atoms in a non-crystalline, irregular, glassy state, not held in a crystalline macrostructure. In nuclear applications where graphite is used as a neutron moderator, accumulation of Wigner energy followed by a sudden, spontaneous release may occur. NASA's Got an App for That", "Online Database Tracks Organic Nano-Particles Across the Universe", "Fire in the hole: After fracking comes coal", "Wonderfuel: Welcome to the age of unconventional gas", Carbon Dioxide Information Analysis Center, "The Carbon Cycle, Climate, and the Long-Term Effects of Fossil Fuel Burning", "Voltatile Products from Carbonaceous Asteroids", 10.1002/(SICI)1521-3773(20000303)39:5<891::AID-ANIE891>3.0.CO;2-E, "Cyclic Polyhydroxy Ketones. Carbon forms a vast number of compounds, more than any other element, with almost ten million compounds described to date,[19] and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions. This exothermic reaction is used in the iron and steel industry to smelt iron and to control the carbon content of steel: Carbon monoxide can be recycled to smelt even more iron: with sulfur to form carbon disulfide and with steam in the coal-gas reaction: 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. Organometallic compounds by definition contain at least one carbon-metal covalent bond. The amount of 14C in the atmosphere and in living organisms is almost constant, but decreases predictably in their bodies after death. Maximum power density of ~ 105 mW m − 2 of composite anode vs. ~ 20 mW m − 2 of graphite anode: Lowy et al. Crude oil is distilled in refineries by the petrochemical industry to produce gasoline, kerosene, and other products. For example, it can form the nitride cyanogen molecule ((CN)2), similar to diatomic halides. For instance, graphite is one of the softest substances, while another crystalline allotrope diamond is one of the hardest materials in nature. [60], In the past, quantities of hydrocarbons were greater. Natural diamonds occur in the rock kimberlite, found in ancient volcanic "necks", or "pipes". These collections, known as functional groups, confer common reactivity patterns and allow for the systematic study and categorization of organic compounds. [66], Carbon-rich asteroids are relatively preponderant in the outer parts of the asteroid belt in our solar system. While a large trade in both types of diamonds exists, the two markets function dramatically differently. Thus, the carbon is bonded to five boron atoms and one hydrogen atom. The calculator below can be used to estimate the density and specific weight of gaseous carbon monoxide at given temperature and pressure. As of 2009, graphene appears to be the strongest material ever tested. The three relatively well-known allotropes of carbon are amorphous carbon, graphite, and diamond. At standard temperature and pressure, it resists all but the strongest oxidizers. [83] Dissolved in water, it forms carbonic acid (H2CO3), but as most compounds with multiple single-bonded oxygens on a single carbon it is unstable. Plastics are made from fossil hydrocarbons, and carbon fiber, made by pyrolysis of synthetic polyester fibers is used to reinforce plastics to form advanced, lightweight composite materials. As such, 1.5%×10−10 of atmospheric carbon dioxide contains carbon-14. However, a recent computational study employing density functional theory methods reached the conclusion that as T → 0 K and p → 0 Pa, diamond becomes more stable than graphite by approximately 1.1 kJ/mol. The raw materials for many of these synthetic substances come from crude oil. Relative atomic mass The mass of an atom relative to that of carbon-12. The carbon cycle is one of the most important of all biological processes. Consequently, once it enters into the body's tissues it is likely to remain there indefinitely. Hope it is of help to you. However, mellitic anhydride is the triple acyl anhydride of mellitic acid; moreover, it contains a benzene ring. [104] Some iron again was left, which the French scientists thought was necessary to the graphite structure. [61] Another source puts the amount added to the atmosphere for the period since 1750 at 879 Gt, and the total going to the atmosphere, sea, and land (such as peat bogs) at almost 2,000 Gt. More specifically, the dication could be described structurally by the formulation [MeC(η5-C5Me5)]2+, making it an "organic metallocene" in which a MeC3+ fragment is bonded to a η5-C5Me5− fragment through all five of the carbons of the ring.[96]. [72][73], There are 15 known isotopes of carbon and the shortest-lived of these is 8C which decays through proton emission and alpha decay and has a half-life of 1.98739 × 10−21 s.[74] The exotic 19C exhibits a nuclear halo, which means its radius is appreciably larger than would be expected if the nucleus were a sphere of constant density.[75]. [127] In these examples, the harm may result from contaminants (e.g., organic chemicals, heavy metals) rather than from the carbon itself. In general, covalent radius decreases with lower coordination number and higher bond order.[24]. All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form at standard temperature and pressure. It is resistant to dissolution or chemical attack, even in the acidic contents of the digestive tract. Exceptions include 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. [49][50] Carbon is abundant in the Sun, stars, comets, and in the atmospheres of most planets. It is also used as a lubricant and a pigment, as a molding material in glass manufacture, in electrodes for dry batteries and in electroplating and electroforming, in brushes for electric motors and as a neutron moderator in nuclear reactors. When combined with oxygen and hydrogen, carbon can form many groups of important biological compounds including sugars, lignans, chitins, alcohols, fats, and aromatic esters, carotenoids and terpenes. This results in a lower bulk electrical conductivity for carbon than for most metals. [84] Through this intermediate, though, resonance-stabilized carbonate ions are produced. [95] 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. The English name carbon comes from the Latin carbo for coal and charcoal,[98] whence also comes the French charbon, meaning charcoal. The most prominent oxide is carbon dioxide (CO2). The CNO cycle is an additional hydrogen fusion mechanism that powers stars, wherein carbon operates as a catalyst. https://en.wikipedia.org/w/index.php?title=Carbon&oldid=990903309, Biology and pharmacology of chemical elements, Wikipedia indefinitely semi-protected pages, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License.