In the example below, the bone must date to sometime between 1.75 and 1.5 million years ago.
As a result, there is a changing ratio of carbon-14 to the more atomically stable carbon-12 involves actually counting individual carbon-14 atoms.
This allows the dating of much older and smaller samples but at a far higher cost.
Over the second half-life, of the atoms remaining decay, which leaves of the original quantity, and so on.
In other words, the change in numbers of atoms follows a geometric scale as illustrated by the graph below.other carbon isotopes in the same ratio as exists in the atmosphere.