Although (Soddy, Nature 92:399–400,1913)inferred the existence of isotopes early lastcentury, it was not until the discovery of theneutron by (Chadwick, Nature 129:312,1932)that isotopes were understood to result fromdiffering numbers of neutrons in atomicnuclei. (Urey, J Chem Soc 1947:562–581,1947) predicted that different isotopes wouldbehave slightly differently in chemical (andphys…