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.
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.
Once the rock cools and solidifies, Argon that is formed by radioactive decay is trapped inside.
As no Argon was present in the rock when it first solidified, all Argon in the rock is due to the radioactive decay of Potassium.
This process is called radiometric or radioactive dating.This is used to date the remains of things that were once living.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.