Quoted from Future Learnthe C-14 method is a radiometric dating method using known decay rates of radioactive isotopes to date an object.
Each radioactive isotope has a fixed rate of decay called a half-life. If you know the isotopes and their decay rates, scientists can calculate how old the fossil is.
The element carbon occurs in nature in three isotopic forms. Carbon 12 (12-C) is stable and represents 98.9% of the carbon in the atmosphere. The remainder (1.1%) consists mostly of Carbon 13 (13-C), which is also stable, and Carbon 14 (C-14) which is unstable – or radioactive.
READ : How to Determine the Age of Fossils, Here’s the Method!
In the atmosphere, only about one in a trillion carbon atoms is C-14 . Most of the C-14 in the atmosphere is produced by the action of cosmic rays on nitrogen (N-14) to produce C-14.
Once C-14 is produced, it begins to decompose back into nitrogen. The atmosphere has constant levels of C-14 – the production of new C-14 in the atmosphere and the decay of C-14 balance each other out in a steady state equilibrium.
If you already know how much C-14 is in living tissue, you can measure the amount of C-14 in a dead plant or animal and then compare it to assess how long it has been dead.
Scientists were able to do this because they knew the decay rate of C-14 (it has a half-life of 5,730 years). The result is the radiocarbon age of the sample.
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