Isotopes, isomers and the fundamental law of radioactive change

Abstract

IN 1861, at the age of 29, William Crookes discovered a new element which he named thallium, thereby commemorating the green line in the spectrum which revealed its existence. In the wisdom of old age, for he was then turned 70, Michael Faraday wrote in congratulation ‘To discover a new element is a very fine thing, but if you could decompose an element and tell us what it is made of—that would be a discovery indeed worth making’. Just about forty years later, in 1903, to be precise, Rutherford, the physicist, and Soddy, the chemist, took the first step towards that greater discovery—the step of recognition; they recognized that the atoms of the radioactive elements are all the time decomposing themselves.