New Scale of Nuclidic Masses and Atomic Weights

Abstract

A discussion is presented of the situation which led to the existence of the chemicai scale (atomic weight of element O = l6) and the physical scale (atomic weight of principal O isotope = 16) and of the considerations that led to their replacement by a new scale. ln 1959, the lnternatlonal Commission of Atomlc Weights recommended the adoption of C12 as the reference species wlth assigned relative mass of 12, since this isotope was acceptable to both chemists and physicists. The lnternational Union of Pure and Applied Physlcs and the International Unlon of Pure and Applled Chemlstry adopted this recommended scale. A table of atomic weights developed from a complete review of experimental data on the basis of the new scale ls presented together wlth a separate table for radloactive elements. (D.L.C.)