Relate radioactive dating techniques to isotopes
The atoms of some chemical elements have different forms, called isotopes.These break down over time in a process scientists call radioactive decay.For example, fission track dating measures the microscopic marks left in crystals by subatomic particles from decaying isotopes.Another example is luminescence dating, which measures the energy from radioactive decay that is trapped inside nearby crystals.
Each isotope is identified with what is called a ‘mass number’.
For example, the decay of potassium-40 to argon-40 is used to date rocks older than 20,000 years, and the decay of uranium-238 to lead-206 is used for rocks older than 1 million years.
Radiocarbon dating measures radioactive isotopes in once-living organic material instead of rock, using the decay of carbon-14 to nitrogen-14.
Others measure the subatomic particles that are emitted as an isotope decays.
Some measure the decay of isotopes more indirectly.