Autore: Pourya Zarshenas
Formato: Copertina flessibile
Pagine: 248
Data Pubblicazione: 2022-05-20
Edizione: 1
Lingua: English

Carbon (C), nonmetallic chemical element in Group 14 (IVa) of the periodic table. Although widely distributed in nature, carbon is not particularly plentiful it makes up only about 0.025 percent of Earths crust yet it forms more compounds than all the other elements combined. In 1961 the isotope carbon12 was selected to replace oxygen as the standard relative to which the atomic weights of all the other elements are measured. Carbon14, which is radioactive, is the isotope used in radiocarbon dating and radiolabeling.On a weight basis, carbon is 19th in order of elemental abundance in Earths crust, and there are estimated to be 3.5 times as many carbon atoms as silicon atoms in the universe. Only hydrogen, helium, oxygen, neon, and nitrogen are atomically more abundant in the cosmos than carbon. Carbon is the cosmic product of the burning of helium, in which three helium nuclei, atomic weight 4, fuse to produce a carbon nucleus, atomic weight 12.In the crust of Earth, elemental carbon is a minor component. However, carbon compounds (i.e., carbonates of magnesium and calcium) form common minerals (e.g., magnesite, dolomite, marble, or limestone).