Radiometric dating , radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon , in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay. Together with stratigraphic principles , radiometric dating methods are used in geochronology to establish the geologic time scale. By allowing the establishment of geological timescales, it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change. Radiometric dating is also used to date archaeological materials, including ancient artifacts.
Carbon from Latin : carbo "coal" is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent —making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon is the 15th most abundant element in the Earth's crust , and the fourth most abundant element in the universe by mass after hydrogen , helium , and oxygen.