By measuring the amounts of Potassium and Argon present we can date volcanic rocks that are millions of years old.
Carbon Dating Another important dating technique is Carbon-14 dating.
Radiometric dating is possible because the radioactive decay of large numbers of radioactive atoms follows a predictable pattern.
This predictability allows scientists to measure the age of an object if they can work out how many radioactive atoms were originally present.
The original radioactive atom is known as a parent isotope, while the atom produced by the decay process is known as a daughter isotope. For example Uranium-235 and Uranium-238 are both Uranium atoms with the same number of protons, but they have a different number of neutrons.
The number used to identify the isotope refers to the total number of particles in the nucleus of each atom.
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.