So if we started with 2 million atoms of carbon-14 in our measured quantity of carbon, then the half-life of radiocarbon will be the time it takes for half, or 1 million, of these atoms to decay.
The radiocarbon half-life or decay rate has been determined at 5,730 years.
After plants and animals perish, however, they no longer replace molecules damaged by radioactive 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 3).
The standard way of expressing the decay rate is called the half-life.5 It’s defined as the time it takes half a given quantity of a radioactive element to decay.Let’s suppose we find a mammoth’s skull, and we want to date it to determine how long ago it lived.We can measure in the laboratory how many carbon-14 atoms are still in the skull. You probably have seen or read news stories about fascinating ancient artifacts.
At an archaeological dig, a piece of wooden tool is unearthed and the archaeologist finds it to be 5,000 years old.
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).