Absolute dating isotopes
Shortly after Becquerel's find, Marie Curie, a French chemist, isolated another highly radioactive element, .
The realisation that radioactive materials emit rays indicated a constant change of those materials from one element to another.
By measuring how long it takes for an unstable element to decay into a stable element and by measuring how much daughter element has been produced by the parent element within a specimen of rock, scientists believe they are able to determine the age of the rock.
The numbers 238 and 206 represent these isotopes' atomic mass.
Prior to 1905 the best and most accepted age of the Earth was that proposed by Lord Kelvin based on the amount of time necessary for the Earth to cool to its present temperature from a completely liquid state.
Although we now recognize lots of problems with that calculation, the age of 25 my was accepted by most physicists, but considered too short by most geologists. Recognition that radioactive decay of atoms occurs in the Earth was important in two respects: Principles of Radiometric Dating Radioactive decay is described in terms of the probability that a constituent particle of the nucleus of an atom will escape through the potential (Energy) barrier which bonds them to the nucleus.
Radiometric Dating - A Brief Explanation Radiometric dating is the primary dating scheme employed by scientists to determine the age of the earth.
Radiometric dating techniques take advantage of the natural decay of radioisotopes.