Abstract

Whom should we credit for the discovery of isotopes? The first suggestion of an idea, the first experimental proof, or the development of a new method that clearly reveals the isotopes? Strömholm and Svedberg, Fajans and Soddy interpreted patterns of radioactive decay, which became confirmed theory on the solid basis of the very accurate atomic weight determinations by Richards and his coworkers. The mass spectrograph measurements by Aston provided major extension of the concept of isotopes to much of the rest of the periodic table. Thus, Strömholm and Svedberg, Fajans and Soddy provided an idea, which Richards proved, and Aston made generally useful. Richards should be listed along with Fajans, Soddy, and Aston for fundamental contributions to establishing isotopes as part of the modern language of science. As much credit should be given to the experimental proof as to the suggestion or naming of the concept.