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Pure Appl. Chem., 2001, Vol. 73, No. 4, pp. 667-683

http://dx.doi.org/10.1351/pac200173040667

INORGANIC CHEMISTRY DIVISION
COMMISSION ON ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCES

Atomic weights of the elements 1999 (IUPAC Technical Report)

T. B. Coplen

U.S. Geological Survey, 431 National Center, Reston, Virginia 20192, USA

Abstract:
The biennial review of atomic-weight, Ar(E), determinations and other cognate data have resulted in changes for the standard atomic weights of the following elements:
element From To
nitrogen 14.006 74 ± 0.000 07 14.0067 ± 0.0002
sulfur 32.066 ± 0.006 32.065 ± 0.005
chlorine 35.4527 ± 0.0009 35.453 ± 0.002
germanium 72.61 ± 0.02 72.64 ± 0.01
xenon 131.29 ± 0.02 131.293 ± 0.006
erbium 167.26 ± 0.03 167.259 ± 0.003
uranium 238.0289 ± 0.0001 238.028 91 ± 0.000 03
Presented are updated tables of the standard atomic weights and their uncertainties estimated by combining experimental uncertainties and terrestrial variabilities. In addition, this report again contains an updated table of relative atomic-mass values and half-lives of selected radioisotopes. Changes in the evaluated isotopic abundance values from those published in 1997 are so minor that an updated list will not be published for the year 1999.
Many elements have a different isotopic composition in some nonterrestrial materials. Some recent data on parent nuclides that might affect isotopic abundances or atomic-weight values are included in this report for the information of the interested scientific community.

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