The pioneering works of E. Rutherford related to radioactivity and nuclear science were contributions to physics, but they also had important implications for chemistry. Thus, in his early study of the ‘emanation’ liberated from thorium and radium Rutherford showed that it was a new element (radon). His theory of radioactive decay sounded the death knell over the old chemical dogma of the immutability of atoms. Likewise, the discovery of the nuclear atom in 1911 led to a new understanding of the periodic system soon developed by N. Bohr, H. Moseley and others. The first artificial transmutation of an element in 1919 was later followed by proton- and deuteron-induced transformations from which Rutherford suggested the existence of mass-3 isotopes of hydrogen and helium. In addition, he was the first to suggest that the still hypothetical neutron might be used as a projectile in nuclear reactions.