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Carbon (from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. [13] Carbon makes up about 0.025 percent of Earth's ...
Carbon concentration in the mantle is very variable, varying by more than a factor of 100 between different parts. [6] [7] The form carbon takes depends on its oxidation state, which depends on the oxygen fugacity of the environment. Carbon dioxide and carbonate are found where the oxygen fugacity is high.
The carbon cycle was first described by Antoine Lavoisier and Joseph Priestley, and popularised by Humphry Davy. [5] The global carbon cycle is now usually divided into the following major reservoirs of carbon (also called carbon pools) interconnected by pathways of exchange: [6] Atmosphere; Terrestrial biosphere
The Lomagundi-Jatuli Carbon Isotope Excursion or Lomagundi-Jatuli Event (LJE) was a carbon isotope excursion that occurred in the Paleoproterozoic between 2.3-2.1 Ga, possessing the largest magnitude and longest duration of positive δ 13 C values found in marine carbonate rocks. [1] [2] The δ 13 C values range from +5 to + 30‰.
Carbon-based photosynthesis life caused a rise in oxygen on Earth. This increase of oxygen helped plate tectonics form the first continents. [10] It is frequently assumed in astrobiology that if life exists elsewhere in the Universe, it will also be carbon-based. [11] [12] Critics, like Carl Sagan in 1973, refer to this assumption as carbon ...
Another allotrope of carbon is a fullerene, which has the form of sheets of carbon atoms folded into a sphere. A fifth allotrope of carbon, discovered in 2003, is called graphene, and is in the form of a layer of carbon atoms arranged in a honeycomb-shaped formation. [6] [14] [15] Silicon has two known allotropes that exist at room temperature.
The two discovered a new element in a molybdenum sample that was used in a cyclotron, the first element to be discovered by synthesis. It had been predicted by Mendeleev in 1871 as eka-manganese. [171] [172] [173] In 1952, Paul W. Merrill found its spectral lines in S-type red giants. [174]
Martin David Kamen (August 27, 1913, Toronto – August 31, 2002, Montecito, California) was an American chemist who, together with Sam Ruben, co-discovered the synthesis of the isotope carbon-14 on February 27, 1940, at the University of California Radiation Laboratory, Berkeley. [1]