3 radioactive elements commonly used in the absolute dating
By far the most common is radioactive dating which involves checking the amount of a given radioactive isotope in a given sample is left over (and calculating from the half-life [the time it takes for a radioactive element/isotope to decay to half the original amount]).
Another one would likely be tree-ring dating which only determines the age of trees by how many rings it has. Radioactive isotopes, to be more precise - because sometimes, one isotope may be stable, while another isotope of the same element is radioactive. Elements of the lanthanide and actinide series are the most radioactive.
Radioactive isotopes in medicine are used to help diagnose certain disease states and isolate regions in the body.
Elements 89-100 are the Actinide series of elements, most of which are radioactive, and some of which can only be made artificially.
The most obvious use for radon is the automobile industry. Uranium is commonly used as a basic fuel for nuclear reactors.
Geologists often need to know the age of material that they find.
Each isotope is identified with what is called a ‘mass number’.
The atoms of some chemical elements have different forms, called isotopes.
Carbon dating is the most common for shorter periods.
Polonium is often considered to be the most radioactive element, but there are far more radioactive elements like nobelium and lawrencium.
anything past bismuth and 2 elements in middle (promethium and another I don't remember).
some researchers believe bismuth is also naturally radioactive, but with a half-life longer than the age of the universe.
Radiometric dating, the measurement of the ratios of radioactive materials within the rocks.