Potassium 40 dating
One out of every 10,000 Potassium atoms is radioactive Potassium-40 (K-40).These each have 19 protons and 21 neutrons in their nucleus.The mass energy of atom is above these of its two neighbours in the family of atoms with 40 nucleons in their nucleus : Argon-40 with one proton less and calcium-40 with one proton more. The beta-minus decay channel leading to calcium_40 is by far the most frequent, but decays leading to argon-40 by electronic capture occurs at a rate of 11 %.Potassium-Argon Dating Potassium-Argon dating is the only viable technique for dating very old archaeological materials.A second problem is that for technical reasons, the measurement of argon and the measurement of potassium have to be made on two different samples, because each measurement requires the destruction of the sample.
It is based on the fact that some of the radioactive isotope of Potassium, Potassium-40 (K-40) ,decays to the gas Argon as Argon-40 (Ar-40).
Potassium occurs in two stable isotopes (Ar atoms trapped inside minerals.