An article in Phys.org announced that the IUPAC (International Union of Pure and Applied Chemistry) voted at a meeting this past August to change the standard atomic weights of 19 elements. Because atomic weights are averages, the number depends upon the amount of the element which is available, as well as the techniques used to measure the weights. The proposed changes are said to be due to the availability of more precise measurements. The changes in weights of the 19 elements will be published next year in the journal Pure and Applied Chemistry.
