Radio carbon dating information
The carbon in their bodies at the time of their death will remain in their bodies until they decompose, or if they become fossilized, then forever. This allows scientists to look at the amount of decay in a fossil’s radioactive carbon and determine a relative date.Radiocarbon dating is only effective for objects and fossils that are less than 50,000 years old.Ninety-nine percent of these also contain six neutrons.The 6 proton 6 neutron atoms are said to have a mass of 12 and are referred to as "carbon-12." The nuclei of the remaining one percent of carbon atoms contain not six but either seven or eight neutrons in addition to the standard six protons.Libby calculated the half-life of carbon-14 as 5568, a figure now known as the Libby half-life.
Most carbon on Earth is not radioactive, but a very small percentage is.
As a result it is always undergoing natural radioactive decay while the abundances of the other isotopes are unchanged.
Carbon-14 is most abundant in atmospheric carbon dioxide because it is constantly being produced by collisions between nitrogen atoms and cosmic rays at the upper limits of the atmosphere.
Carbon-14 has a relatively short half-life of 5730 years, meaning that the amount of carbon-14 in a sample is halved over the course of 5730 years due to radioactive decay.
By about ten half-lives, or 58,000 years, the amount of carbon-14 left in the fossil is very little- about 1/1000 of the original number of carbon-14 atoms in the fossil.