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).These excited neutrons then collide with nitrogen atoms in the atmosphere, changing them into radioactive carbon-14 atoms.
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.The reason is that, as long as the organism is alive, it replaces any carbon molecule that has decayed into nitrogen.After plants and animals perish, however, they no longer replace molecules damaged by radiocarbon decay.Instead, the radiocarbon atoms in their bodies slowly decay away, so the ratio of carbon-14 atoms to regular carbon atoms will steadily decrease over time (Figure 1c).Let’s suppose we find a mammoth’s skull and we want to date it to determine how long ago it lived.