14 carbon dating
Both Carbon-12 and Carbon-13 are stable, but Carbon-14 decays by very weak beta decay to nitrogen-14 with a half-life of approximately 5,730 years.
After the organism dies it stops taking in new carbon.
Animals and people take in carbon-14 by eating the plants.
Isotopes participate in the same chemical reactions but often at differing rates.
When isotopes are to be designated specifically, the chemical symbol is expanded to identify the mass (for example, C is not stable.
Ninety-nine percent of these also contain six neutrons.
The 6 proton 6 neutron atoms are said to have a mass of 12 and are referred to as "carbon-12." The nuclei of the remaining one percent of carbon atoms contain not six but either seven or eight neutrons in addition to the standard six protons.
The pathway from the plant to the molecule may have been indirect or lengthy, involving multiple physical, chemical, and biological processes.