The Rutherford Memorial Lecture, 1971: Evolution of the elements

Abstract

I chose this title because, as your Chairman has emphasized, this is a historic occasion. More than 50 years ago Ernest Rutherford used this title when he returned to New Zealand in 1914 and lectured here, in Canterbury College. On that occasion he talked about the spontaneous disintegrations that radioactive nuclei undergo, with the emission of α, β and γ radiation; how one radioactive element changes into another and how uranium and thorium eventually transform to various isotopes of lead. The understanding of the laws of radioactive change was the result of collaboration between Rutherford & Soddy in a long series of experiments at McGill; this was the first of three of Rutherford’s most important results-the other two were: ‘the discovery of the nucleus of the atom following experiments of Geiger & Marsden at Manchester’ and ‘the detection of nuclear interactions’. Under the same title as used by Rutherford here in 1914 I want tonight to talk about how the chemical elements of which the Earth and Sun are made, may have evolved. As a start I would like to present to you in figure 1 some of the facts that need explaining — the relative abundance of the 300 or so naturally occurring types of atom — the isotopes of the various chemical elements. Their relative abundance tells us something about how the elements must have evolved. The graph displayed shows the results appropriate to the Solar System. One realizes that terrestrial or meteoritic abundances are seriously distorted by loss of volatile materials - but most of one’s data is collected from the Earth and meteorites, so we have to put up with it. The distribution, corrected as well as possible for the loss of volatile materials, is often called the ‘universal’ abundance for the elements, but this is overstating its significance.