Two situations where we can do this involve Potassium-40 atoms and Carbon-14 atoms.
All radioactive atoms decay to become a more stable kind of atom.
The process of dating finds the two ratios between uranium-235 and lead-207; and uranium-238 and lead-206.
The three main parameters that have to be set are the original amount of uranium and lead in the sample, the rate at which uranium and lead enter and leave the sample, and how much the rate of decay changes.
Uranium-lead dating uses four different isotopes to find the age of the rock.
Some of the different kinds of radioactive atoms used to date objects are shown in the following table: Potassium-Argon Dating Potassium atoms are used to date rocks that have formed from molten rock. Argon is an inert gasit does not chemically bond to other atoms.
Argon in molten rock can just bubble out and escape.