Radiocarbon dating diagram
After radiocarbon forms, the nuclei of the carbon-14 atoms are unstable, so over time they progressively decay back to nuclei of stable nitrogen-14.3 A neutron breaks down to a proton and an electron, and the electron is ejected. The ejected electrons are called beta particles and make up what is called beta radiation. Different carbon-14 atoms revert to nitrogen-14 at different times, which explains why radiocarbon decay is considered a random process.
To measure the rate of decay, a suitable detector records the number of beta particles ejected from a measured quantity of carbon over a period of time, say a month (for illustration purposes).
When animals eat the plants, the carbon-14 enters their bodies.
The carbon-14 in their bodies breaks down to nitrogen-14 and escapes at the same rate as new carbon-14 is added. CARBON-14 IS DEPLETED (Figure 1c): When an animal dies the carbon-14 continues to break down to nitrogen-14 and escapes, while no new carbon-14 is added.
These rapidly combine with oxygen atoms (the second most abundant element in the atmosphere, at 21%) to form carbon dioxide (CO).