Chemistry of Isotopes: Isotope chemistry has opened new areas of chemical physics, geochemistry, and molecular biology.

With the exception of the field of chemical kinetics, a brief survey has been presented of the principles of isotope chemistry and their utility in the ever-unfolding panorama of scientific research. We have come a long way since Soddy and Fajans arrived at the concept of chemical twins-isotopes. There are still places to go.