Scientific definition of carbon dating
Plus, get practice tests, quizzes, and personalized coaching to help you succeed.Try it risk-free Ever wondered how scientists know the age of old bones in an ancient site or how old a scrap of linen is?
In the late 1940s, American chemist Willard Libby developed a method for determining when the death of an organism had occurred.
Radiocarbon present in molecules of atmospheric carbon dioxide enters the biological carbon cycle: it is absorbed from the air by green plants and then passed on to animals through the food chain.
Radiocarbon decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food.
You will notice that after around 40,000 years (or 8 half-lives), the amount left is starting to become very small, less than 1%.
Scientists often use the value of 10 half-lives to indicate when a radioactive isotope will be gone, or rather, when a very negligible amount is still left.
A very small percentage of carbon, however, consists of the isotope carbon 14, or , which is unstable.