The energies involved are so large, and the nucleus is so small that physical conditions in the Earth (i.e. The rate of decay or rate of change of the number N of particles is proportional to the number present at any time, i.e.The half-life is the amount of time it takes for one half of the initial amount of the parent, radioactive isotope, to decay to the daughter isotope.Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old.Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.Protons and neutrons make up the center (nucleus) of the atom, and electrons form shells around the nucleus.The number of protons in the nucleus of an atom determines the element.The only problem is that we only know the number of daughter atoms now present, and some of those may have been present prior to the start of our clock. The reason for this is that Rb has become distributed unequally through the Earth over time.

Many people have been led to believe that radiometric dating methods have proved the earth to be billions of years old.The object's approximate age can then be figured out using the known rate of decay of the isotope.Radiocarbon dating is one kind of radiometric dating, used for determining the age of organic remains that are less than 50,000 years old.To see how we actually use this information to date rocks, consider the following: Usually, we know the amount, N, of an isotope present today, and the amount of a daughter element produced by decay, D*.By definition, D* = N-1) (2) Now we can calculate the age if we know the number of daughter atoms produced by decay, D* and the number of parent atoms now present, N.Lane, geology professor at Tufts University, as chairman.