Chemical workings of carbon dating

25 Feb

Since carbon is fundamental to life, occurring along with hydrogen in all organic compounds, the detection of such an isotope might form the basis for a method to establish the age of ancient materials. Libby, a Professor of Chemistry at the University of Chicago, predicted that a radioactive isotope of carbon, known as carbon-14, would be found to occur in nature.For a rare event it happens pretty damn often — one million carbon-14 atoms in your body decay into nitrogen every minute!But don't panic — of the 800,000,000,000,000,000,000,000,000 carbon atoms in every one of us, about 800,000,000,000,000 are carbon-14, so we've got a few to spare.Radiocarbon dating is used to work out the age of things that died up to 50,000 years ago. As far as working out the age of long-dead things goes, carbon has got a few things going for it. The proteins, carbohydrates and fats that make up much of our tissues are all based on carbon.Everything from the fibres in the Shroud of Turin to Otzi the Iceman has had their birthday determined the carbon-14 way. There's plenty of hydrogen, oxygen and nitrogen in living things too, but carbon's got something none of them do — a radioactive isotope that can take thousands of years to decay.Atoms of the same element that have different numbers of neutrons are called isotopes. Most carbon on Earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13.

To understand radiocarbon dating, you first have to understand the word Although an element’s number of protons cannot change, the number of neutrons can vary slightly from each atom.This has to do with figuring out the age of ancient things.If you could watch a single atom of a radioactive isotope, U-238, for example, you wouldn’t be able to predict when that particular atom might decay.This decay is an example of an exponential decay, shown in the figure below.Knowing about half-lives is important because it enables you to determine when a sample of radioactive material is safe to handle.