What isotopes are used for radioactive dating
The object's approximate age can then be figured out using the known rate of decay of the isotope.For organic materials, the comparison is between the current ratio of a radioactive isotope to a stable isotope of the same element and the known ratio of the two isotopes in living organisms.
The atoms of some chemical elements have different forms, called isotopes.
Radiocarbon dating measures radioactive isotopes in once-living organic material instead of rock, using the decay of carbon-14 to nitrogen-14.
Because of the fairly fast decay rate of carbon-14, it can only be used on material up to about 60,000 years old.
The realisation that radioactive materials emit rays indicated a constant change of those materials from one element to another.
The New Zealand physicist Ernest Rutherford, suggested in 1905 that the exact age of a rock could be measured by means of radioactivity.