Explicit use of et al. Archived PDF from the original on Archived from the original PDF on Lukens "Production of radiocarbon in tree rings by lightning bolts", Journal of Geophysical Research, Volume 78, Issue 26, October , pp. Physicists show that thunderstorms trigger nuclear reactions in the atmosphere. Progress in Nuclear Energy. A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center.
Oak Ridge National Laboratory. Modeling the Influence of Diet". Institute for Radiological Protection and Nuclear Safety.
Archived from the original on 25 September Retrieved 9 Dec All other atmospheric carbon dioxide comes from young sources—namely land-use changes for example, cutting down a forest in order to create a farm and exchange with the ocean and terrestrial biosphere. This makes 14C an ideal tracer of carbon dioxide coming from the combustion of fossil fuels. Scientists can use 14C measurements to determine the age of carbon dioxide collected in air samples, and from this can calculate what proportion of the carbon dioxide in the sample comes from fossil fuels.
National Council on Radiation Protection and Measurements. Retrieved from " https: Isotopes of carbon Environmental isotopes. Webarchive template wayback links CS1 maint: Views Read Edit View history. In other projects Wikimedia Commons.
It does not react with sulfuric acid , hydrochloric acid , chlorine or any alkalis. At elevated temperatures, carbon reacts with oxygen to form carbon oxides and will rob oxygen from metal oxides to leave the elemental metal. This exothermic reaction is used in the iron and steel industry to smelt iron and to control the carbon content of steel:. 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.
Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes. The three relatively well-known allotropes of carbon are amorphous carbon , graphite , and diamond. Once considered exotic, fullerenes are nowadays commonly synthesized and used in research; they include buckyballs ,   carbon nanotubes ,  carbon nanobuds  and nanofibers.
Graphene is a two-dimensional sheet of carbon with the atoms arranged in a hexagonal lattice.
As of , graphene appears to be the strongest material ever tested. It could also be used to safely store hydrogen for use in a hydrogen based engine in cars. The amorphous form is an assortment of carbon atoms in a non-crystalline, irregular, glassy state, not held in a crystalline macrostructure.
It is present as a powder, and is the main constituent of substances such as charcoal , lampblack soot and activated carbon. At normal pressures, carbon takes the form of graphite, in which each atom is bonded trigonally to three others in a plane composed of fused hexagonal rings, just like those in aromatic hydrocarbons. This gives graphite its softness and its cleaving properties the sheets slip easily past one another. This results in a lower bulk electrical conductivity for carbon than for most metals.
The delocalization also accounts for the energetic stability of graphite over diamond at room temperature. At very high pressures, carbon forms the more compact allotrope, diamond , having nearly twice the density of graphite. Here, each atom is bonded tetrahedrally to four others, forming a 3-dimensional network of puckered six-membered rings of atoms.
Diamond has the same cubic structure as silicon and germanium , and because of the strength of the carbon-carbon bonds , it is the hardest naturally occurring substance measured by resistance to scratching. The bottom left corner of the phase diagram for carbon has not been scrutinized experimentally. Fullerenes are a synthetic crystalline formation with a graphite-like structure, but in place of flat hexagonal cells only, some of the cells of which fullerenes are formed may be pentagons, nonplanar hexagons, or even heptagons of carbon atoms.
The sheets are thus warped into spheres, ellipses, or cylinders. The properties of fullerenes split into buckyballs, buckytubes, and nanobuds have not yet been fully analyzed and represent an intense area of research in nanomaterials.
The names fullerene and buckyball are given after Richard Buckminster Fuller , popularizer of geodesic domes , which resemble the structure of fullerenes. The buckyballs are fairly large molecules formed completely of carbon bonded trigonally, forming spheroids the best-known and simplest is the soccerball-shaped C 60 buckminsterfullerene.
Radiocarbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of. Pages in category "Radiocarbon dating". The following 11 pages are in this category, out of 11 total. This list may not reflect recent changes (learn more).
Of the other discovered allotropes, carbon nanofoam is a ferromagnetic allotrope discovered in It consists of a low-density cluster-assembly of carbon atoms strung together in a loose three-dimensional web, in which the atoms are bonded trigonally in six- and seven-membered rings.
Carbon in this modification is linear with sp orbital hybridization , and is a polymer with alternating single and triple bonds. In , a team at the North Carolina State University announced the development of another allotrope they have dubbed Q-carbon , created by a high energy low duration laser pulse on amorphous carbon dust.
The carbon cycle is considerably more complicated than this short loop; for example, some carbon dioxide is dissolved in the oceans; if bacteria do not consume it, dead plant or animal matter may become petroleum or coal , which releases carbon when burned. Natural diamonds occur in the rock kimberlite , found in ancient volcanic "necks", or "pipes". The method works to about 60, years old. After one half-life has elapsed, one half of the atoms of the nuclide in question will have decayed into a "daughter" nuclide or decay product. In their publication they proposed the name carbone Latin carbonum for the element in graphite which was given off as a gas upon burning graphite. Pages with empty citations IKhemikhali. These measurements are used in the subsequent calculation of the age of the sample.
Q-carbon is reported to exhibit ferromagetism, fluorescence , and a hardness superior to diamonds. Carbon is the fourth most abundant chemical element in the observable universe by mass after hydrogen, helium, and oxygen. Carbon is abundant in the Sun , stars , comets , and in the atmospheres of most planets. PAHs seem to have been formed "a couple of billion years" after the Big Bang , are widespread throughout the universe, and are associated with new stars and exoplanets.
It has been estimated that the solid earth as a whole contains ppm of carbon, with ppm in the core and ppm in the combined mantle and crust. This is much more than the amount of carbon in the oceans or atmosphere below. Hydrocarbons such as coal , petroleum , and natural gas contain carbon as well. Carbon is also found in methane hydrates in polar regions and under the seas. Various estimates put this carbon between , Gt ,  or 3, Gt.
In the past, quantities of hydrocarbons were greater. According to one source, in the period from to about gigatonnes of carbon were released as carbon dioxide to the atmosphere from burning of fossil fuels. Natural diamonds occur in the rock kimberlite , found in ancient volcanic "necks", or "pipes". Diamonds are now also being recovered from the ocean floor off the Cape of Good Hope.
Carbon-rich asteroids are relatively preponderant in the outer parts of the asteroid belt in our solar system. These asteroids have not yet been directly sampled by scientists. The asteroids can be used in hypothetical space-based carbon mining , which may be possible in the future, but is currently technologically impossible. Isotopes of carbon are atomic nuclei that contain six protons plus a number of neutrons varying from 2 to Carbon has two stable, naturally occurring isotopes.
Carbon 14 C is a naturally occurring radioisotope , created in the upper atmosphere lower stratosphere and upper troposphere by interaction of nitrogen with cosmic rays. The amount of 14 C in the atmosphere and in living organisms is almost constant, but decreases predictably in their bodies after death. There are 15 known isotopes of carbon and the shortest-lived of these is 8 C which decays through proton emission and alpha decay and has a half-life of 1. Formation of the carbon atomic nucleus occurs within a giant or supergiant star through the triple-alpha process.
This requires a nearly simultaneous collision of three alpha particles helium nuclei , as the products of further nuclear fusion reactions of helium with hydrogen or another helium nucleus produce lithium-5 and beryllium-8 respectively, both of which are highly unstable and decay almost instantly back into smaller nuclei. According to current physical cosmology theory, carbon is formed in the interiors of stars on the horizontal branch. This dust becomes component material for the formation of the next-generation star systems with accreted planets.
The CNO cycle is an additional hydrogen fusion mechanism that powers stars, wherein carbon operates as a catalyst. Rotational transitions of various isotopic forms of carbon monoxide for example, 12 CO, 13 CO, and 18 CO are detectable in the submillimeter wavelength range, and are used in the study of newly forming stars in molecular clouds. Under terrestrial conditions, conversion of one element to another is very rare.
Therefore, the amount of carbon on Earth is effectively constant. Thus, processes that use carbon must obtain it from somewhere and dispose of it somewhere else. The paths of carbon in the environment form the carbon cycle. For example, photosynthetic plants draw carbon dioxide from the atmosphere or seawater and build it into biomass, as in the Calvin cycle , a process of carbon fixation. Some of this biomass is eaten by animals, while some carbon is exhaled by animals as carbon dioxide. The carbon cycle is considerably more complicated than this short loop; for example, some carbon dioxide is dissolved in the oceans; if bacteria do not consume it, dead plant or animal matter may become petroleum or coal , which releases carbon when burned.
Carbon can form very long chains of interconnecting carbon—carbon bonds , a property that is called catenation. Carbon-carbon bonds are strong and stable. Through catenation, carbon forms a countless number of compounds. A tally of unique compounds shows that more contain carbon than do not. 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. A hydrocarbon backbone can be substituted by other atoms, known as heteroatoms. Common heteroatoms that appear in organic compounds include oxygen, nitrogen, sulfur, phosphorus, and the nonradioactive halogens, as well as the metals lithium and magnesium.
Organic compounds containing bonds to metal are known as organometallic compounds see below. Certain groupings of atoms, often including heteroatoms, recur in large numbers of organic compounds. These collections, known as functional groups , confer common reactivity patterns and allow for the systematic study and categorization of organic compounds. Chain length, shape and functional groups all affect the properties of organic molecules.
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. 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.
Carbon occurs in all known organic life and is the basis of organic chemistry.
When united with hydrogen , it forms various hydrocarbons that are important to industry as refrigerants , lubricants , solvents , 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. Commonly carbon-containing compounds which are associated with minerals or which do not contain bonds to the other carbon atoms, halogens, or hydrogen, are treated separately from classical organic compounds ; the definition is not rigid, and the classification of some compounds can vary from author to author see reference articles above.
Among these are the simple oxides of carbon. The most prominent oxide is carbon dioxide CO 2. This was once the principal constituent of the paleoatmosphere , but is a minor component of the Earth's atmosphere today. Some important minerals are carbonates, notably calcite. Carbon disulfide CS 2 is similar. The other common oxide is carbon monoxide CO. It is formed by incomplete combustion, and is a colorless, odorless gas.
The molecules each contain a triple bond and are fairly polar , resulting in a tendency to bind permanently to hemoglobin molecules, displacing oxygen, which has a lower binding affinity. For example, it can form the nitride cyanogen molecule CN 2 , similar to diatomic halides.
Other uncommon oxides are carbon suboxide C 3 O 2 ,  the unstable dicarbon monoxide C 2 O ,   carbon trioxide CO 3 ,   cyclopentanepentone C 5 O 5 ,  cyclohexanehexone C 6 O 6 ,  and mellitic anhydride C 12 O 9. However, mellitic anhydride is the triple acyl anhydride of mellitic acid; moreover, it contains a benzene ring.
Thus, many chemists consider it to be organic. These anions are also associated with methane and acetylene , both very weak acids. With an electronegativity of 2. A few carbides are covalent lattices, like carborundum SiC , which resembles diamond. Nevertheless, even the most polar and salt-like of carbides are not completely ionic compounds. Organometallic compounds by definition contain at least one carbon-metal covalent bond.
Many metal carbonyls and metal cyanides exist for example, tetracarbonylnickel and potassium ferricyanide ; some workers consider metal carbonyl and cyanide complexes without other carbon ligands to be purely inorganic, and not organometallic. I-radioactive isotope ye-carbon, i-carbon, isenokusetyenziswa ukuzama ukubona okokuba ingaba zindala kangakanani na ezinye ii-objects okanye izinto okanye kusetyenziswe yona ukujonga okokuba ife nini na into. Ukuba nje into iphezu komhlaba ikwathatha i-carbon, isixa se-carbon esishiyekayo siyafana.
Xa i-object okanye into iyeka ukuthatha i-carbon, isixa se-carbon siyehla. Kuba i-halfu-yobomi how long it takes for half of a radioactive isotope to go away be-carbon 14 ingama years,  ii-scientists zingabona okokuba ingaba into leyo indala kangakanani na ngokuthi zibone okokuba ingakanani na i-carbon 14 eshiyekileyo. I-Carbon ifumaneka kwiindawo ezininzi apha emhlabeni.
Yaqala yenziwa kwiinkwenkwezi zakudala. I-Carbon yi-element yesine ukuxhaphaka elangeni. Uninzi lwe-carbon lufumaneka emHlabeni ngamalahle. I-Graphite yona ifumaneka kwiindawo ezomileyo ezifana kanye ne ntlango , eziquka i-Sri Lanka, i-Madagascar, kwakunye ne- Russia. Idayimani inqabile kwaye ifumaneka kakhulu e-Africa. I-Carbon ikwafumaneka kwezinye ii-meteorites.