carbon [Lat.,=charcoal], nonmetallic chemical element; symbol C; at. no. 6; at. wt. 12.011; m.p. about 3,550°C;; graphite sublimes about 3,375°C;; b.p. 4,827°C;; sp. gr. 1.8–2.1 (amorphous), 1.9–2.3 (graphite), 3.15–3.53 (diamond); valence +2, +3, +4, or −4.

Properties and Isotopes

Carbon is found free in nature in at least four distinct forms (see allotropy allotropy (əlŏ`trəpē) [Gr.,=other form].
..... Click the link for more information. ). One form, graphite graphite (grăf`īt), an allotropic form of carbon , known also as plumbago and black lead.
..... Click the link for more information. , is a very soft, dark gray or black, lustrous material with either a hexagonal or rhombohedral crystalline structure. Diamond diamond, mineral, one of two crystalline forms of the element carbon (see allotropy ), the hardest natural substance known, used as a gem and in industry.

Properties

..... Click the link for more information. , a second crystalline form, is the hardest substance known. In a third form, the so-called amorphous carbon, the element occurs partly free and partly combined with other elements; charcoal charcoal, substance obtained by partial burning or carbonization (destructive distillation ) of organic material. It is largely pure carbon . The entry of air during the carbonization process is controlled so that the organic material does not turn to ash, as in a
..... Click the link for more information. , coal coal, fuel substance of plant origin, largely or almost entirely composed of carbon with varying amounts of mineral matter.

Types

There is a complete series of carbonaceous fuels, which differ from each other in the relative amounts of moisture,
..... Click the link for more information. , coke coke, substance obtained by the destructive distillation of bituminous coal . Coke bears the same relation to coal as does charcoal to wood. A hard, gray, massive, porous fuel, coke is the solid residue remaining after bituminous coal is heated to a high temperature
..... Click the link for more information. , lampblack, peat peat, soil material consisting of partially decomposed organic matter; found in swamps and bogs in various parts of the temperate zone. It is formed by the slow decay of successive layers of aquatic and semiaquatic plants, e.g., sedges, reeds, rushes, and mosses.
..... Click the link for more information. , and lignite lignite (lĭg`nīt) or brown coal,
..... Click the link for more information. are some sources of amorphous carbon. A fourth form contains the fullerenes fullerides. Among these are conducting films of alkali metal-doped fullerenes and superconductors (potassium-doped T_c 18°K;, rubidium-doped T_c 30°K;). Fullerenes also have been used to produce tiny diamonds and thin diamond films.
..... Click the link for more information. , stable molecules consisting of carbon atoms that arrange themselves into 12 pentagonal faces and any number greater than 1 of hexagonal faces. The most prominent of the fullerenes is buckminsterfullerene buckminsterfullerene (bŭk'mĭnstərf
..... Click the link for more information. , a spheroidal molecule, resembling a soccer ball, consisting of 60 carbon atoms. A fifth form, "white" carbon, is believed to exist. Carbon has the capacity to act chemically both as a metal and as a nonmetal. It is a constituent of all organic matter.

Carbon has 13 known isotopes, which have from 2 to 14 neutrons in the nucleus and mass numbers from 8 to 20. Carbon-12 was chosen by IUPAC in 1961 as the basis for atomic weights atomic weight, mean (weighted average) of the masses of all the naturally occurring isotopes of a chemical element , as contrasted with atomic mass , which is the mass of any individual isotope.
..... Click the link for more information. ; it is assigned an atomic mass of exactly 12 atomic mass units. Carbon-13 absorbs radio waves and is used in nuclear magnetic resonance spectrometry to study organic compounds. Carbon-14, which has a half-life of 5,730 years, is a naturally occurring isotope that can also be produced in a nuclear reactor. It is used extensively as a research tool in tracer studies; a compound synthesized with carbon-14 is said to be "tagged" and can be traced through a chemical or biochemical reaction. Carbon-14 has been used in the study of such problems as utilization of foods in animal nutrition, catalytic petroleum processes, photosynthesis, and the mechanism of aging in steel. It is also used for determining the age of archaeological specimens (see dating dating, the determination of the age of an object, of a natural phenomenon, or of a series of events. There are two basic types of dating methods, relative and absolute.
..... Click the link for more information. ).

Compounds

There are more carbon compounds than there are compounds of all other elements combined. The study of carbon compounds, both natural and synthetic, is called organic chemistry. Plastics plastic, any organic material with the ability to flow into a desired shape when heat and pressure are applied to it and to retain the shape when they are withdrawn.
..... Click the link for more information. , foods, textiles textiles, all fabrics made by weaving, felting, knitting, braiding, or netting, from the various textile fibers (see fiber ).

Types of Textiles

..... Click the link for more information. , and many other common substances contain carbon. Hydrocarbon hydrocarbon (hī'drōkär`bən), any organic compound composed solely of the elements hydrogen and carbon.
..... Click the link for more information. fuels (e.g., natural gas), marsh gas, and the gases resulting from the combustion of fuels (e.g., carbon monoxide and carbon dioxide) are compounds of carbon. With oxygen and a metallic element, carbon forms many important carbonates, such as calcium carbonate (limestone) and sodium carbonate (soda). Certain active metals react with it to make industrially important carbides, such as silicon carbide (an abrasive known as carborundum), calcium carbide, used for producing acetylene gas, and tungsten carbide, an extremely hard substance used for rock drills and metalworking tools.

Natural Occurrence and Uses

Carbon has been known to humans in its various forms since ancient times. Although carbon makes up only .032% of the earth's crust, it is very widely distributed and forms a vast number of compounds. Carbon exists in the stars; a series of thermonuclear reactions called the carbon cycle (see nucleosynthesis nucleosynthesis or nucleogenesis, in astronomy, production of all the chemical elements from the simplest element, hydrogen, by thermonuclear reactions within stars, supernovas, and in the big bang at the beginning of the universe (see nucleus ;
..... Click the link for more information. ) is a source of energy for some stars. Carbon in the form of diamonds has been found in meteorites. Coke is used as a fuel in the production of iron. Carbon electrodes are widely used in electrical apparatus. The "lead" of the ordinary pencil is graphite mixed with clay. The successful linking in the 1940s of carbon with silicon has led to the development of a vast number of new substances known collectively as the silicones silicone, polymer in which atoms of silicon and oxygen alternate in a chain; various organic radicals, such as the methyl group, CH₃, are bound to the silicon atoms.
..... Click the link for more information. .

Biological Importance

All living organisms contain carbon; the human body is about 18% carbon by weight. In green plants carbon dioxide and water are combined to form simple sugars (carbohydrates carbohydrate, any member of a large class of chemical compounds that includes sugars, starches, cellulose, and related compounds. These compounds are produced naturally by green plants from carbon dioxide and water (see photosynthesis ).
..... Click the link for more information. ); light from the sun provides the energy for this process (photosynthesis photosynthesis (fō'tōsĭn`thəsĭs)
..... Click the link for more information. ). The energy from the sun is stored in the chemical bonds of the sugar molecule. Anabolism, the synthesis of complex compounds (such as fats fats and oils, group of organic substances that form an important part of the diet and also are useful in many industries. The fats are usually solid, the oils generally liquid at ordinary room temperatures.
..... Click the link for more information. , proteins protein, any of the group of highly complex organic compounds found in all living cells and comprising the most abundant class of all biological molecules. Protein comprises approximately 50% of cellular dry weight.
..... Click the link for more information. , and nucleic acids nucleic acid, any of a group of organic substances found in the chromosomes of living cells and viruses that play a central role in the storage and replication of hereditary information and in the expression of this information through protein synthesis.
..... Click the link for more information. ) from simpler substances, involves the utilization of energy stored by photosynthesis. Catabolism is the release of stored energy by the oxidative destruction of organic compounds; water and carbon dioxide are two byproducts of catabolism. This continuing synthesis and degradation involving carbon dioxide is known as the biological carbon cycle carbon cycle, in biology, the exchange of carbon between living organisms and the nonliving environment. Inorganic carbon dioxide in the atmosphere is converted by plants into simple carbohydrates, which are then used to produce more complex substances.
..... Click the link for more information. .

Bibliography

See P. L. Walker, Jr., and P. A. Thrower, ed., Chemistry and Physics of Carbon (11 vol., 1966–74); H. O. Pierson, Handbook of Carbon, Graphite, Diamond, and Fullerenes: Properties, Processing, and Applications (1993).

carbon

Nonmetallic chemical element, chemical symbol C, atomic number 6. The usual stable isotope is carbon-12; carbon-13, another stable isotope, makes up 1% of natural carbon. Carbon-14 is the most stable and best known of five radioactive isotopes (see radioactivity); its half-life of approximately 5,730 years makes it useful in carbon-14 dating and radiolabeling of research compounds. Carbon occurs in four known allotropes: diamond, graphite, carbon black (amorphous carbon including coal, coke, and charcoal), and hollow cage molecules called fullerenes. Carbon forms more compounds than all other elements combined; several million carbon compounds are known. Each carbon atom forms four bonds (four single bonds, two single and one double bond, two double bonds, or one single and one triple bond) with up to four other atoms. Multitudes of chain, branched, ring, and three-dimensional structures can occur. The study of these carbon compounds and their properties and reactions is organic chemistry (see organic compound). With hydrogen, oxygen, nitrogen, and a few other elements whose small amounts belie their important roles, carbon forms the compounds that make up all living things: proteins, carbohydrates, lipids, and nucleic acids. Biochemistry is the study of how those compounds are synthesized and broken down and how they associate with each other in living organisms. Organisms consume carbon and return it to the environment in the carbon cycle. Carbon dioxide, produced when carbon is burned and from biological processes, makes up about 0.03% of the air, and carbon occurs in Earth's crust as carbonate rocks and the hydrocarbons in coal, petroleum, and natural gas. The oceans contain large amounts of dissolved carbon dioxide and carbonates.

Carbon

See Cocoa.

carbon

a. a nonmetallic element existing in the three crystalline forms: graphite, diamond, and buckminsterfullerene: occurring in carbon dioxide, coal, oil, and all organic compounds. The isotope carbon-12 has been adopted as the standard for atomic wt.; carbon-14, a radioisotope with a half-life of 5700 years, is used in radiocarbon dating and as a tracer. Symbol: C; atomic no.: 6; atomic wt.: 12.011; valency: 2, 3, or 4; relative density: 1.8--2.1 (amorphous), 1.9--2.3 (graphite), 3.15--3.53 (diamond); sublimes at 3367±25°C; boiling pt.: 4827°C.

b. (as modifier): a carbon compound

2. a carbon electrode used in a carbon-arc light or in carbon-arc welding

3. a rod or plate, made of carbon, used in some types of battery

carbon [′kär·bən]

(chemistry)

A nonmetallic chemical element, symbol C, atomic number 6, atomic weight 12.01115; occurs freely as diamond, graphite, and coal.

carbon (redirected from carbon coated)

Properties and Isotopes

Properties

Types

Compounds

Types of Textiles

Natural Occurrence and Uses

Biological Importance

Bibliography

carbon

Carbon

carbon
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