Methods of dating prentice hall
In these cases, usually the half-life of interest in radiometric dating is the longest one in the chain, which is the rate-limiting factor in the ultimate transformation of the radioactive nuclide into its stable daughter.
Isotopic systems that have been exploited for radiometric dating have half-lives ranging from only about 10 years (e.g., tritium) to over 100 billion years (e.g., samarium-147).
The basic equation of radiometric dating requires that neither the parent nuclide nor the daughter product can enter or leave the material after its formation.
For instance, carbon-14 has a half-life of 5,730 years.
After an organism has been dead for 60,000 years, so little carbon-14 is left that accurate dating cannot be established.
The only exceptions are nuclides that decay by the process of electron capture, such as beryllium-7, strontium-85, and zirconium-89, whose decay rate may be affected by local electron density.
For all other nuclides, the proportion of the original nuclide to its decay products changes in a predictable way as the original nuclide decays over time.