Carbon

Carbon (), but as most compounds with multiple single-bonded oxygens on a single carbon it is unstable.] 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. Other uncommon oxides are carbon suboxide (chem|C|3|O|2), [citeweb|title= Compounds of carbon: carbon suboxide|url=http://www.webelements.com/webelements/compounds/text/C/C3O2-504643.html|accessdate=2007-12-03] the unstable dicarbon monoxide (C₂O), [citejournal|author= Bayes K.|title=Photolysis of Carbon Suboxide|journal=Journal of the American Chemical Society|volume=83|year=1961|pages=3712–3713|doi=10.1021/ja01478a033] [citejournal|author=Anderson D. J.|coauthor=Rosenfeld R. N.|title=Photodissociation of Carbon Suboxide|journal=Journal of Chemical Physics|volume=94|year=1991|pages=7852–7867|doi=10.1063/1.460121] and even carbon trioxide (CO₃). [citejournal|title=A theoretical study of the structure and properties of carbon trioxide|author=Sabin, J. R.|coauthor=Kim, H.|journal=Chemical Physics Letters|volume=11|issue=5|pages=593–597|date=11/1971|doi=10.1016/0009-2614(71)87010-0] [citejournal|title=Carbon Trioxide: Its Production, Infrared Spectrum, and Structure Studied in a Matrix of Solid CO₂|journal=The Journal of Chemical Physics|year=1966|volume=45|issue=12|pages=4469–4481|doi=10.1063/1.1727526|author=Moll N. G., Clutter D. R., Thompson W. E.]

With reactive metals, such as tungsten, carbon forms either carbides (C^4–), or acetylides (C₂^2–) 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, [cite book |author= L. Pauling |title= The Nature of the Chemical Bond |edition= 3^rd ed. |publisher= Cornell University Press |location= Ithaca, NY |year= 1960 |pages= 93 ] carbon prefers to form covalent bonds. A few carbides are covalent lattices, like carborundum (SiC), which resembles diamond.

Organic compounds

Carbon has the ability to form very long chains interconnecting C-C bonds. This property is called catenation. Carbon-carbon bonds are strong, and stable.Fact|date=November 2007 This property allows carbon to form an almost infinite number of compounds; in fact, there are more known carbon-containing compounds than all the compounds of the other chemical elements combined except those of hydrogen (because almost all organic compounds contain hydrogen too).

The simplest form of an organic molecule is the hydrocarbon—a large family of organic molecules that are composed of hydrogen atoms bonded to a chain of carbon atoms. Chain length, side chains and functional groups all affect the properties of organic molecules. By IUPAC's definition, all the other organic compounds are functionalized compounds of hydrocarbons.Fact|date=December 2007

Carbon occurs in all organic life and is the basis of organic chemistry. When united with hydrogen, it forms various flammable compounds called hydrocarbons which are important to industry as chemical feedstock 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 sugars,lignans, chitins, alcohols, fats, and 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 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.

History and etymology

The English name "carbon" comes from the Latin "carbo" for coal and charcoal, [Shorter Oxford English Dictionary, Oxford University Press] and hence comes French "charbon", meaning charcoal. In German, Dutch and Danish, the names for carbon are "Kohlenstoff", "koolstof" and "kulstof" respectively, all literally meaning coal-substance.

Carbon was discovered in prehistory and was known in the forms of soot and charcoal to the earliest human civilizations. Diamonds were known probably as early as 2500 BCE in China, while carbon in the forms of charcoal was made around Roman times by the same chemistry as it is today, by heating wood in a pyramid covered with clay to exclude air.cite news | url = http://news.bbc.co.uk/2/hi/science/nature/4555235.stm | title = Chinese made first use of diamond | publisher = BBC News | date= 17 May 2005 | accessdate = 2007-03-21] [cite web |url=http://www.vanderkrogt.net/elements/elem/c.html |title=Carbonium/Carbon at Elementymology & Elements Multidict |author= Peter van der Krogt |last=van der Krogt |first=Peter |accessdate=2007-12-21]

In 1722, René A. F. de Réaumur demonstrated that iron was transformed into steel through the absorption of some substance, now known to be carbon. [cite book |author=R-A Ferchault de Réaumur |last=Ferchault de Réaumur |first=R-A |year=1722 |title=L'art de convertir le fer forgé en acier, et l'art d'adoucir le fer fondu, ou de faire des ouvrages de fer fondu aussi finis que le fer forgé (English translation from 1956) |location=Paris, Chicago] In 1772, Antoine Lavoisier showed that diamonds are a form of carbon, when he burned samples of carbon and diamond then showed that neither produced any water and that both released the same amount of carbon dioxide per gram.
Carl Wilhelm Scheele showed that graphite, which had been thought of as a form of lead, was instead a type of carbon. [citeweb|author=Senese, Fred|url=http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/discovery-of-carbon.shtml | title=Who discovered carbon? | publisher=Frostburg State University |accessdate=2007-11-24] In 1786, the French scientists Claude Louis Berthollet, Gaspard Monge and C. A. Vandermonde then showed that this substance was carbon. [citebook|author=Federico Giolitti|year=1914
title=The Cementation of Iron and Steel|publisher=McGraw-Hill Book Company, inc.] In their publication they proposed the name carbone (Latin carbonum) for this element. Antoine Lavoisier listed carbon as an element in his 1789 textbook. [citeweb|author=Senese,Fred |date=September 9, 2009|url=http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/discovery-of-carbon.shtml|title=Who discovered carbon?|publisher=Frostburg State University|accessdate=2007-11-24 ]

A new allotrope of carbon, fullerene, that was discovered in 1985 [citejournal|journal=Nature|volume=318|pages=162–163|year=1985|doi=10.1038/318162a0|title=C⁶⁰: Buckminsterfullerene|author=H. W. Kroto, J. R. Heath, S. C. O'Brien, R. F. Curl and R. E. Smalley] includes nanostructured forms such as buckyballs and nanotubes.citeweb|url=http://www.ch.ic.ac.uk/local/projects/unwin/Fullerenes.html|title=Fullerenes(An Overview)|author=Peter Unwin|accessdate=2007-12-08] Their discoverers received the Nobel Prize in Chemistry in 1996. [cite web |url=http://nobelprize.org/nobel_prizes/chemistry/laureates/1996/index.html |title=The Nobel Prize in Chemistry 1996 "for their discovery of fullerenes" |accessdate=2007-12-21] The resulting renewed interest in new forms, lead to the discovery of further exotic allotropes, including glassy carbon, and the realization that "amorphous carbon" is not strictly amorphous.cite journal |author=PJF Harris |last=Harris |first=PJF |year=2004 |title=Fullerene-related structure of commercial glassy carbons |journal=Philosophical Magazine, 84, 3159–3167 |doi=10.1007/s10562-007-9125-6 |volume=116 |pages=122]

Production

Graphite

Commercially viable natural deposits of graphite occur in many parts of the world, but the most important sources economically are in China, India, Brazil, and North Korea. [ [http://minerals.usgs.gov/minerals/pubs/commodity/graphite/myb1-2006-graph.pdf USGS Minerals Yearbook: Graphite, 2006] ] Graphite deposits are of metamorphic origin, found in association with quartz, mica and feldspars in schists, gneisses and metamorphosed sandstones and limestone as lenses or veins, sometimes of a metre or more in thickness. Deposits of graphite in Borrowdale, Cumberland, England were at first of sufficient size and purity that, until the 1800s, pencils were made simply by sawing blocks of natural graphite into strips before encasing the strips in wood. Today, smaller deposits of graphite are obtained by crushing the parent rock and floating the lighter graphite out on water.

According to the USGS, world production of natural graphite in 2006 was 1.03 million tonnes and in 2005 was 1.04 million tonnes (revised), of which the following major exporters produced: China produced 720,000 tonnes in both 2006 and 2005, Brazil 75,600 tonnes in 2006 and 75,515 tonnes in 2005 (revised), Canada 28,000 tonnes in both years, and Mexico (amorphous) 12,500 tonnes in 2006 and 12,357 tonnes in 2005 (revised). In addition, there are two specialist producers: Sri Lanka produced 3,200 tonnes in 2006 and 3,000 tonnes in 2005 of lump or vein graphite, and Madagascar produced 15,000 tonnes in both years, a large portion of it "crucible grade" or very large flake graphite. Some other producers produce very small amounts of "crucible grade".

According to the USGS, U.S. (synthetic) graphite electrode production in 2006 was 132,000 tonnes valued at $495 million and in 2005 was 146,000 tonnes valued at $391 million, and high-modulus graphite (carbon) fiber production in 2006 was 8,160 tonnes valued at $172 million and in 2005 was 7,020 tonnes valued at $134 million.

Diamond

The diamond supply chain is controlled by a limited number of powerful businesses, and is also highly concentrated in a small number of locations around the world.Fact|date=October 2008

Only a very small fraction of the diamond ore consists of actual diamonds. The ore is crushed, during which care has to be taken in order to prevent larger diamonds from being destroyed in this process and subsequently the particles are sorted by density. Today, diamonds are located in the diamond-rich density fraction with the help of X-ray fluorescence, after which the final sorting steps are done by hand. Before the use of X-rays became commonplace, the separation was done with grease belts; diamonds have a stronger tendency to stick to grease than the other minerals in the ore.

Historically diamonds were known to be found only in alluvial deposits in southern India.cite book | last = Catelle | first = W.R. | title = The Diamond | publisher = John Lane Company | year = 1911 Page 159 discussion on Alluvial diamonds in India and elsewhere as well as earliest finds ] India led the world in diamond production from the time of their discovery in approximately the 9th century BCEcite book | last = Ball | first = V. | title = Diamonds, Gold and Coal of India | publisher = London, Truebner & Co. | year = 1881 Ball was a Geologist in British service. Chapter I, Page 1 ] to the mid-18th century AD, but the commercial potential of these sources had been exhausted by the late 18th century and at that time India was eclipsed by Brazil where the first non-Indian diamonds were found in 1725.Fact|date=September 2008

Diamond production of primary deposits (kimberlites and lamproites) only started in the 1870s after the discovery of the Diamond fields in South Africa. Production has increased over time and now an accumulated total of 4.5 billion carats have been mined since that date.cite journal| last = Janse | first= A. J. A. | title= Global Rough Diamond Production Since 1870 | journal= Gems and Gemology | volume= XLIII |issue= Summer 2007| pages=98–119 |publisher=GIA | date=2007 ] Interestingly 20% of that amount has been mined in the last 5 years alone and during the last ten years 9 new mines have started production while 4 more are waiting to be opened soon. Most of these mines are located in Canada, Zimbabwe, Angola, and one in Russia.

In the US, diamonds have been found in Arkansas, Colorado, and Montana.cite journal| last = Lorenz| first= V. | title=Argyle in Western Australia: The world's richest diamondiferous pipe; its past and future| journal=Gemmologie, Zeitschrift der Deutschen Gemmologischen Gesellschaft | volume=56 |issue=1/2| pages=35–40 |publisher = DGemG | date=2007 ] [cite web|url=http://www.montanastandard.com/articles/2004/10/18/featuresbusiness/hjjfijicjbhdjc.txt |title= Microscopic diamond found in Montana | publisher = The Montana Standard | date= 2004-10-17| accessdate = 2008-10-10 ] In 2004, a startling discovery of a microscopic diamond in the US [cite web | url = http://www.livescience.com/environment/wyoming_diamond_041019.html | publisher = Livescience.com |date= |accessdate=2008-09-12 | title = Microscopic Diamond Found in Montana | first = Sarah | last = Cooke | date = 2004-10-19 12:25 ] led to the January 2008 bulk-sampling of kimberlite pipes in a remote part of Montana. [cite web|url=http://www.deltamine.com/release2008-01-08.htm |title=Delta :: News / Press Releases / Publications |publisher=Deltamine.com |date= |accessdate=2008-09-12]

Today, most commercially viable diamond deposits are in Russia, Botswana, Australia and the Democratic Republic of Congo. [cite web | url = http://gnn.tv/videos/2/The_Diamond_Life | title = The Diamond Life | publisher = Guerrilla News Network | first = Stephen | last = Marshall |coauthors = Shore, Josh |accessdate = 2008-10-10 | date = 2004-10-22] In 2005, Russia produced almost one-fifth of the global diamond output, reports the British Geological Survey. Australia boasts the richest diamondiferous pipe with production reaching peak levels of convert|42|MT per year in the 1990s.

There are also commercial deposits being actively mined in the Northwest Territories of Canada, Siberia (mostly in Yakutia territory, for example Mir pipe and Udachnaya pipe), Brazil, and in Northern and Western Australia. Diamond prospectors continue to search the globe for diamond-bearing kimberlite and lamproite pipes.

Other forms

:"amorphous?, charcoal, fullerenes?"

Applications

Carbon is essential to all known living systems, and without it life as we know it could not exist (see alternative biochemistry). The major economic use of carbon other than food and wood is in the form of hydrocarbons, most notably the fossil fuel methane gas and crude oil (petroleum). Crude oil is used by the petrochemical industry to produce, amongst others, gasoline and kerosene, through a distillation process, in refineries. Cellulose is a natural, carbon-containing polymer produced by plants in the form of cotton, linen, hemp. Cellulose is mainly used for maintaining structure in plants. Commercially valuable carbon polymers of animal origin include wool, cashmere and silk. Plastics are made from synthetic carbon polymers, often with oxygen and nitrogen atoms included at regular intervals in the main polymer chain. The raw materials for many of these synthetic substances come from crude oil.

The uses of carbon and its compounds are extremely varied. It can form alloys with iron, of which the most common is carbon steel. Graphite is combined with clays to form the 'lead' used in pencils used for writing and drawing. It is also used as a lubricant and a pigment, as a moulding 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.

Charcoal is used as a drawing material in artwork, for grilling, and in many other uses including iron smelting. Wood, coal and oil are used as fuel for production of energy and space heating. Gem quality diamond is used in jewelry, and Industrial diamonds are used in drilling, cutting and polishing tools for machining metals and stone. Plastics are made from fossil hydrocarbons, and carbon fibre, made by pyrolysis of synthetic polyester fibres is used to reinforce plastics to form advanced, lightweight composite materials. Carbon fiber is made by pyrolysis of extruded and stretched filaments of polyacrylonitrile (PAN) and other organic substances. The crystallographic structure and mechanical properties of the fiber depend on the type of starting material, and on the subsequent processing. Carbon fibres made from PAN have structure resembling narrow filaments of graphite, but thermal processing may re-order the structure into a continuous rolled sheet Fact|date=November 2007. The result is fibers with higher specific tensile strength than steel.Fact|date=November 2007

Carbon black is used as the black pigment in printing ink, artist's oil paint and water colours, carbon paper, automotive finishes, India ink and laser printer toner. Carbon black is also used as a filler in rubber products such as tyres and in plastic compounds. Activated charcoal is used as an absorbent and adsorbent in filter material in applications as diverse as gas masks, water purification and kitchen extractor hoods and in medicine to absorb toxins, poisons, or gases from the digestive system. Carbon is used in chemical reduction at high temperatures. coke is used to reduce iron ore into iron. Case hardening of steel is achieved by heating finished steel components in carbon powder. Carbides of silicon, tungsten, boron and titanium, are among the hardest known materials, and are used as abrasives in cutting and grinding tools. Carbon compounds make up most of the materials used in clothing, such as natural and synthetic textiles and leather, and almost all of the interior surfaces in the built environment other than glass, stone and metal.

Diamonds

The diamond industry can be broadly separated into two basically distinct categories: one dealing with gem-grade diamonds and another for industrial-grade diamonds. While a large trade in both types of diamonds exists, the two markets act in dramatically different ways.

A large trade in gem-grade diamonds exists. Unlike precious metals such as gold or platinum, gem diamonds do not trade as a commodity: there is a substantial mark-up in the sale of diamonds, and there is not a very active market for resale of diamonds. One hallmark of the trade in gem-quality diamonds is its remarkable concentration: wholesale trade and diamond cutting is limited to a few locations. 92% of diamond pieces cut in 2003 were in Surat, Gujarat, India. [cite web | url = http://www.time.com/time/magazine/article/0,9171,501040419-610100,00.html | title = Uncommon Brilliance - TIME | publisher = Time.com | first = Aravind Adiga | last = Surat |date= 2004-04-12 | accessdate = 2008-09-12] Other important centers of diamond cutting and trading are Antwerp, where the International Gemological Institute is based, London, New York, Tel Aviv, Amsterdam. A single company—De Beers—controls a significant proportion of the trade in diamonds. They are based in Johannesburg, South Africa and London, England.

The production and distribution of diamonds is largely consolidated in the hands of a few key players, and concentrated in traditional diamond trading centers. The most important being Antwerp, where 80% of all rough diamonds, 50% of all cut diamonds and more than 50% of all rough, cut and industrial diamonds combined are handled.Fact|date=November 2007 This makes Antwerp the de facto 'world diamond capital'. New York, however, along with the rest of the United States, is where almost 80% of the world's diamonds are sold, including auction sales. Also, the largest and most unusually shaped rough diamonds end up in New York. The De Beers owns or controls a significant portion of the world's rough diamond production facilities (mines) and distribution channels for gem-quality diamonds. The company and its subsidiaries own mines that produce some 40 percent of annual world diamond production. At one time it was thought over 80 percent of the world's rough diamonds passed through the Diamond Trading Company (DTC, a subsidiary of De Beers) in London, but presently the figure is estimated at less than 50 percent. The De Beers diamond advertising campaign is acknowledged as one of the most successful and innovative campaigns in history. N. W. Ayer & Son, the advertising firm retained by De Beers in the mid-20th century, succeeded in reviving the American diamond market and opened up new markets, even in countries where no diamond tradition had existed before. N.W. Ayer's multifaceted marketing campaign included product placement, advertising the diamond itself rather than the De Beers brand, and building associations with celebrities and royalty. This coordinated campaign has lasted decades and continues today; it is perhaps best captured by the slogan "a diamond is forever".

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 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 20,000 kg annually), 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 the 1950s; another 3 billion carats (600 metric tons) of synthetic diamond is produced annually for industrial use. The dominant industrial use of diamond is in cutting, drilling, grinding, and polishing. Most uses of diamonds in these technologies do not require large diamonds; in fact, most diamonds that are gem-quality except for their small size, can find an industrial use. Diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications. Specialized applications include use in laboratories as containment for high pressure experiments (see diamond anvil cell), high-performance bearings, and limited use in specialized windows. With the continuing advances being made in the production of synthetic diamonds, future applications are beginning to become feasible. Garnering much excitement is the possible use of diamond as a semiconductor suitable to build microchips from, or the use of diamond as a heat sink in electronics.

Precautions

Pure carbon has extremely low toxicity and can be handled and even ingested safely in the form of graphite or charcoal. It is resistant to dissolution or chemical attack, even in the acidic contents of the digestive tract, for example. Consequently if it gets into body tissues it is likely to remain there indefinitely. Carbon black was probably one of the first pigments to be used for tattooing, and Ötzi the Iceman was found to have carbon tattoos that survived during his life and for 5200 years after his death. [cite journal | first = Leopold | coauthors = Moser, Maximilian; Spindler, Konrad; Bahr, Frank; Egarter-Vigl, Eduard; Dohr, Gottfried | last = Dorfer | year = 1998 | title = 5200-year old acupuncture in Central Europe? | journal = Science | volume = 282 | pages = 242–243 | doi = 10.1126/science.282.5387.239f] However, inhalation of coal dust or soot (carbon black) in large quantities can be dangerous, irritating lung tissues and causing the congestive lung disease coalworker's pneumoconiosis. Similarly, diamond dust used as an abrasive can do harm if ingested or inhaled. Microparticles of carbon are produced in diesel engine exhaust fumes, and may accumulate in the lungs. [cite journal | last = Donaldson | first = K | coauthors = Stone, V.; Clouter, A.; Renwick, L.; MacNee, W. | year = 2001 | title = Ultrafine particles | journal = Occupational and Environmental Medicine | volume = 58 | pages = 211–216 | url = http://oem.bmj.com/cgi/content/extract/58/3/211] In these examples, the harmful effects may result from contamination of the carbon particles, with organic chemicals or heavy metals for example, rather than from the carbon itself.

Carbon may also burn vigorously and brightly in the presence of air at high temperatures, as in the Windscale fire, which was caused by sudden release of stored Wigner energy in the graphite core. Large accumulations of coal, which have remained inert for hundred of millions of years in the absence of oxygen, may spontaneously combust when exposed to air, for example in coal mine waste tips. The great variety of carbon compounds include such lethal poisons as tetrodotoxin, the lectin ricin from seeds of the castor oil plant "Ricinus communis", cyanide (CN^-) and carbon monoxide; and such essentials to life as glucose and protein.

See also

* Carbon chauvinism
* Carbon footprint
* Low-carbon economy
* Organic chemistry
* Timeline of carbon nanotubes

References

* " [http://lbruno.home.cern.ch/lbruno/documents/Bibliography/LHC_Note_78.pdf On Graphite Transformations at High Temperature and Pressure Induced by Absorption of the LHC Beam] ", J.M. Zazula, 1997

External links

* [http://www.youtube.com/watch?v=wmC8Dg4n-ZA Carbon - Periodic Table of Videos]
* [http://www.britannica.com/eb/article-80956/carbon-group-element Carbon on Britannica]
* [http://www.webelements.com/carbon/ WebElements.com – Carbon]
* [http://www.chemicool.com/elements/carbon.html Chemicool.com – Carbon]
* [http://education.jlab.org/itselemental/ele006.html It's Elemental – Carbon]
* [http://invsee.asu.edu/nmodules/Carbonmod/everywhere.html Extensive Carbon page at asu.edu]
* [http://electrochem.cwru.edu/ed/encycl/art-c01-carbon.htm Electrochemical uses of carbon]
* [http://www.compchemwiki.org/index.php?title=Carbon Computational Chemistry Wiki]
* [http://www.forskning.no/Artikler/2006/juni/1149432180.36 Carbon - Super Stuff. Animation with sound and interactive 3D-models.]
* [http://www.bbc.co.uk/radio4/history/inourtime/inourtime_20060615.shtml BBC Radio 4 series "In Our Time", on "Carbon, the basis of life", 15 June 2006]
* [http://canadaconnects.ca/chemistry/1009/ Introduction to Carbon Properties geared for High School students.]
* [http://octettruss.kilu.de/diamond.html diamond 3D animation]