Radiocarbon dating works by comparing the three different isotopes of carbon. Isotopes of a particular element have the same number of protons in their nucleus, but different numbers of neutrons. Most 14C is produced in the upper atmosphere where neutrons, which are produced by cosmic rays, react with 14N atoms.

What are three things that can be radiocarbon dated?

C-14 dating is only applicable to organic and some inorganic materials (not applicable to metals). Gas proportional counting, liquid scintillation counting and accelerator mass spectrometry are the three principal radiocarbon dating methods.