Physical Constants Metrics
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Atomic weight

Se · selenium

셀레늄

Takeaway
  • Recommended or revised 5 times between 1902 and 2024 (first record 1902, latest revision 2013).
  • The one revision whose previous recommendation had an uncertainty kept the new value inside the previous (expanded) range.
  • The current standard atomic weight is 78.971(8) (recommended in 2013).
0+10⁻³−10⁻³+10⁻²−10⁻²19001920194019601980200020201961 scale change
Relative deviation from the current (or last) value, symmetric-log axis. Bars: uncertainty (expanded range); open circles: no uncertainty; orange boxes: intervals.
Yearyear of the recommendationValue (as printed)as printed in CIAAW's table; digits in parentheses are the uncertainty (expanded range) in the last digitsNotationvalue(uncertainty), interval or no uncertaintyScalebefore 1961 oxygen = 16, from 1961 ¹²C = 12Value, ¹²C scalepre-1961 values multiplied by 15.9994/16z vs previous(new − previous) ÷ previous uncertaintyReportDOI of the CIAAW report
190279.1no uncertaintyO=1679.0970337510.1007/BF01370337
190379.2no uncertaintyO=1679.1970310.1021/ja02003a001
193478.96no uncertaintyO=1678.95703910.1039/JR9340000499
196978.96(3)value(uncertainty)12C=1278.9610.1351/pac197021010091
201378.971(8)value(uncertainty)12C=1278.9710.36710.1515/pac-2015-0305

Source: Standard atomic weights © IUPAC/CIAAW 2016–2024. Commission on Isotopic Abundances and Atomic Weights, Historical changes of standard atomic weights (compiled by J. Meija), https://www.ciaaw.org/historical-atomic-weights.htm