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Carbon



Name Carbon
Atomic Number 6
Atomic Weight 12.0107
Symbol C
Melting Point ( °C ) 3500
Boiling Point ( °C ) 4827
Density (g/cm3) 2.26
Earth crust (%) 0.094
Discovery (Year) ancient
Group 14
Electron configuration [He] 2s2 2p2
Ionization energy (eV) 11.2603

Carbon is the sixth element on the periodic table, with an atomic number of six and an atomic mass of 12.0107 amu. In the periodic table of elements, carbon is found in Group 14 and Period 2. <ref>Bentor, Lenon(2006)."Periodic Table".Retrieved January 20, 2009, from http://www.chemicalelements.com/elements/c.html</ref> Carbon is the sixth most abundant element in the universe and plays a dominant role in the chemistry as the basis of all life on Earth. <ref>Gagdon,Steve(2008)."Jefferson".Retrieved January 20, 2009, from http://education.jlab.org/itselemental/ele006.html</ref> As a non-metal, carbon is unique in its chemical properties because it forms better substances than the total addition of all the other elements combined with each other.

Discovery

The date of discovery and the discoverer of carbon are unknown, several authors suggested charcoal (a form of carbon) has been known since ancient times. The charcoal has been used as fuel for thousands of years. In 1789 Antoine Lavoisier named the element "carbon" because it comes from the Latin word carbo meaning "charcoal".<ref>Flores, Kenneth(2006). "Periodic Table of Elements". Los Alamos. Retrieved January 20, 2009 from http://environamentalchemistry.com/yogi/periodic/C.html.</ref>

The Mole

The SI unit mole is based on the isotope carbon-12. CITATION REQUIRED

Isotopes

In ecology, there has been an advancement in methodological studies in the past several years of the 20th century. One of the central progressions is the growth of steady isotope procedures. Many biogeochemical processes are accompanied by changes in the ratio between stable isotopes of carbon and nitrogen (12C/13C and 14N/15N), which allows different ecosystem components and different ecosystems to be distinguished by their isotopic composition. <ref name="Tiunov"> Tiunov, A.(2007).'Biology Bulletin of the Russian Academy of Sciences Volume 34, Number 4, August 2007 , pp. 395-407(13)'. Stable isotopes of carbon and nitrogen in soil ecological studies.Retrieved February 3, 2009 from http://www.ingentaconnect.com/content/maik/bibu</ref> Analysis of isotopic composition makes it possible to trace matter and energy flows through biological systems and to evaluate the rate of many ecological processes.<ref name="Tiunov" /> The main concepts and methods of stable isotope ecology and patterns of stable isotope fractionation during organic matter decomposition are considered with special emphasis on the fractionation of isotopes in food chains and the use of stable isotope studies of trophic relationships between soil animals in the field. <ref name="Winter">Winter, M.(2009)."WebElements Periodic Table".Retrieved February 3, 2009 from, http://www.webelements.com/carbon/</ref>

Chemical Properties

One of the properties that makes carbon unique is its ability to create four covalent bonds allowing it to link to itself in order to create carbon chains of various lengths and configurations, or to connect to non-carbon atoms in order to form compounds with unique and specialized chemical properties. <ref name="Johnston">Johnston, B. (1994). Cavendish, Sir Henry. Collier's Encyclopedia. New York:P.F. Collier's</ref> Hydrogen plays a special role in carbon because whenever a carbon atom connects to a hydrogen atom the carbon chain ends and creates hydrocarbons.There are nearly ten million known carbon compounds in organic chemistry. <ref name="Johnston" /> Some of the most common carbon compounds are: carbon dioxide(CO2), carbon monoxide(CO), carbon disulfide(CS2), chloroform(CHCl3), carbon tetrachloride(CCl4), methane(CH4),ethylene(C2H4), acetylene(C2H2),Benzene(C6H6), ethyl alcohol(C2H5OH) and acetic acid(CH3COOH).<ref name="Cleveland">Cleveland, Cutler J.(2008)."Carbon".Retrieved January 20, 2009, from http://www.eoearth.org/article/Carbon</ref>Carbon forms three gaseous components with oxygen: carbon monoxide, CO, carbon dioxide, CO2, and carbon sub oxide, C3O2.<ref name="Cleveland" />

Physical Properties

Carbon exits in three well-defined allotropic forms: amorphous, graphite, and diamond.<ref>Chavez, Richard(2005)."Lenntech". January 20, 2009, from http://www.lenntech.com/Periodic-chart-elements/c-en.html</ref>Amorphous carbon is formed when a material containing carbon is burned without having enough oxygen for it to burn completely. <ref name="Winter" />Grafite, one of the softest forms of cabon, is mostly used to make lead for pencils.Diamond, the third naturally occuring form of carbon, one of the hardest substances known, is made by sqeezing grafite under high temperatures and pressures for several days or weeks. <ref name="Winter" /> Commercial diamonds are widely used in the preparation of grinding and cutting tools. <ref name="Johnston" /> Carbon can also be added to steel to make steel and steel castings with grafite.

Uses of Carbon

Graphite combined with clays form the 'lead' used in pencils. Diamond is used for decorative purposes, and also as drill bits. Carbon added to iron makes steel. Carbon is used for control rods in nuclear reactors. Graphite carbon in a powdered, caked form is used as charcoal for cooking, artwork and other uses. Charcoal pills are used in medicine in pill or powder form to adsorb toxins or poisons from the digestive system. <ref> Math and Science Activity Center (1999). Carbon Atom.Retrieved February 5, 2009 from,http://www.edinformatics.com/math_science/c_atom.htm </ref> Elemental carbon exists in several forms, each of which has its own physical characteristics. Two of its well-defined forms, diamond and graphite, are crystalline in structure, but they differ in physical properties because the arrangements of the atoms in their structures are dissimilar. A third form, called fullerene, consists of a variety of molecules composed entirely of carbon. Yet another form, known as carbon black, is amorphous in structure and includes charcoal, lampblack, coal, and coke, although X-ray examination has revealed that these substances do possess a low degree of crystallinity. Diamond and graphite occur naturally on Earth, and they also can be produced synthetically; they are chemically inert but do combine with oxygen at high temperatures, just as amorphous carbon does. Fullerene was serendipitously discovered in 1985 as a synthetic product in the course of laboratory experiments to simulate the chemistry in the atmosphere of giant stars.<ref> carbon. (2009). In Encyclopædia Britannica. Retrieved February 08, 2009, from Encyclopædia Britannica Online: http://www.britannica.com/EBchecked/topic/94732/carbon</ref>




References

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