ATOMIC WEIGHTS OF THE ELEMENTS 1995 (REPRINTED FROM INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY FROM PURE APPL. CHEM. VOL 68, PG 2339, 1996)

The biennial review of atomic weight, A(r)(E), determinations and othe r cognate data has resulted in changes for the standard atomic weight of 21 elements. The five most significant changes are: boron from 10.8 11+/-0.005 to 10.811+/-0.007; carbon from 12.011+/-0.001 to 12.0107+/- 0.0008; arsenic from 74.92159+/-0.00002 to 74.92160+/-0.00002; cerium from 140.115+/-0.004 to 140.116+/-0.001; and platinum 195.08+/-0.03 to 195.078+/-0.002. An annotation for potassium has been changed in the Table of Standard Atomic Weights. To eliminate possible confusion in t he reporting of relative lithium isotope-ratio data, the Commission re commends that such data be expressed using Li-7/Li-6 ratios and that r eporting using Li-6/Li-7 ratios be discontinued. Because relative isot ope-ratio data for sulfur are commonly being expressed on noncorrespon ding scales, the Commission recommends that such isotopic data be expr essed relative to VCDT (Vienna Canon Diablo Troilite) on a scale such that S-34/S-32 Of IAEAS-1 silver sulfide is 0.9997 times that of VCDT. Many elements have a different isotopic composition in some nonterres trial materials. Some recent data on oxygen are included in this artic le for the information of the interested scientific community. (C) 199 7 American Institute of Physics and American Chemical Society.