—carbonless, adj./kahr"beuhn/, n.1. Chem. a widely distributed element that forms organic compounds in combination with hydrogen, oxygen, etc., and that occurs in a pure state as diamond and graphite, and in an impure state as charcoal. Symbol: C; at. wt.: 12.011; at. no.: 6; sp. gr.: (of diamond) 3.51 at 20°C; (of graphite) 2.26 at 20°C.2. See carbon copy.3. a sheet of carbon paper.4. Elect.a. the carbon rod through which current is conducted between the electrode holder and the arc in carbon arc lighting or welding.b. the rod or plate, composed in part of carbon, used in batteries.[1780-90; < F carbone, coinage based on L carbon- (s. of carbo) charcoal]
* * *IThe 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.II(as used in expressions)carbon 14 dating
* * *county, eastern Pennsylvania, U.S., flanked to the north by the Pocono Mountains and to the south by Blue Mountain and located midway between the cities of Wilkes-Barre and Allentown. It consists of a mountainous region lying largely in the Appalachian Ridge and Valley physiographic province. The principal waterways are the Lehigh River and Tobyhanna, Quakake, Nesquehoning, Mahoning, Lizard, and Aquashicola creeks, as well as Penn Forest and Wild Creek reservoirs. State parks include Hickory Run, Lehigh Gorge, and Beltzville, which surrounds Beltzville Lake. The Appalachian National Scenic Trail follows the ridgeline of Blue Mountain.Lehighton was laid out on the site of Gnadenhutten, a Moravian settlement dating from 1746 that was destroyed during the French and Indian War. Anthracite coal was discovered in the region as early as 1791, but it was not mined commercially until the early 19th century, with the introduction of canals and railroads to the area—including a gravity-powered railroad that was the first of its kind in the United States (1828). The county was created in 1843 and named for its abundant coal deposits. In 1954 Mauch Chunk merged with East Mauch Chunk to form Jim Thorpe, the county seat, in commemoration of the American Indian athlete (Thorpe, Jim); his remains were interred in a nearby mausoleum.The county's economy is based on health care services, textile manufacturing, and anthracite coal mining. Area 383 square miles (991 square km). Pop. (2000) 58,802; (2007 est.) 63,242.
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