Chemical dating carbon
The radiocarbon half-life or decay rate has been determined at 5,730 years.
Next comes the question of how scientists use this knowledge to date things.
If we know what fraction of the carbon atoms are radioactive, we can also calculate how many radiocarbon atoms are in the lump.
Knowing the number of atoms that decayed in our sample over a month, we can calculate the radiocarbon decay rate.
Many people assume that rocks are dated at “millions of years” based on radiocarbon (carbon-14) dating. The most well-known of all the radiometric dating methods is radiocarbon dating.
Carbon-14 can yield dates of only “thousands of years” before it all breaks down.
In contrast, radiocarbon forms continually today in the earth’s upper atmosphere.
We can measure in the laboratory how many carbon-14 atoms are still in the skull.
If we assume that the mammoth originally had the same number of carbon- 14 atoms in its bones as living animals do today (estimated at one carbon-14 atom for every trillion carbon-12 atoms), then, because we also know the radiocarbon decay rate, we can calculate how long ago the mammoth died. This dating method is similar to the principle behind an hourglass.6 The sand grains that originally filled the top bowl represent the carbon-14 atoms in the living mammoth just before it died.
Radiocarbon then enters animals as they consume the plants (Figure 1b).
So even we humans are radioactive because of trace amounts of radiocarbon in our bodies.