There are about two dozen decay pairs used for dating.
Uranium 235 decay to lead has a half-life of 713 million years, so it is well suited to dating the universe.
Choosing the best method for radiocarbon dating depends on the quantity of available sample or, in the case of expensive materials, how much of it you can afford to be destroyed.
AMS dating, for example, involves burning a sample to convert it to graphite.
All ordinary matter is made up of combinations of chemical elements, each with its own atomic number, indicating the number of protons in the atomic nucleus.
Additionally, elements may exist in different isotopes, with each isotope of an element differing in the number of neutrons in the nucleus.
and is now the principal source of information about the absolute age of rocks and other geological features, including the age of fossilized life forms or the age of the Earth itself, and can also be used to date a wide range of natural and man-made materials.
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.There are two techniques for dating in archaeological sites: relative and absolute dating.Relative dating stems from the idea that something is younger or older relative to something else.C14 is continually being created and decaying, leading to an equilibrium state in the atmosphere.When the carbon dioxide, containing C14 as well as stable C12 and C13, is taken in by plants it is no longer exposed to the intense cosmic ray bombardment in the upper atmosphere, so the carbon 14 isotope decays without being replenished.