What materials can be dated with radiocarbon dating
By measuring the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of the artifact.
When these energetic neutrons collide with a nitrogen-14 (seven protons, seven neutrons) atom it turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons).
After the organism dies it stops taking in new carbon.
Radiation counters are used to detect the electrons given off by decaying Carbon-14 as it turns into nitrogen.
After the organism dies, carbon-14 continues to decay without being replaced.
To measure the amount of radiocarbon left in a artifact, scientists burn a small piece to convert it into carbon dioxide gas.