For the first time in history, a change will be made to the
atomic weights of some elements listed on the Table of Standard
Atomic Weights of the chemical elements found in the inside
covers of chemistry textbooks worldwide. The International Union
of Pure and Applied Chemistry’s (IUPAC) Commission on Isotopic
Abundances and Atomic Weights is publishing a new table that
will express atomic weights of ten elements as intervals, rather
than as single standard values. The new table is the result of
cooperative research supported by the U.S. Geological Survey,
IUPAC, and other contributing Commission members and
institutions. Standard atomic weights commonly are thought of as
constants of nature, despite the fact that atomic weights of
many common chemical elements show variations as a result of
physical, chemical and biological processes. “For more than a
century and a half, many were taught to use standard atomic
weights — a single value — found on the inside cover of
chemistry textbooks and on the periodic tab