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Atomic weight

Th · thorium

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Takeaway
  • Recommended or revised 10 times between 1902 and 2024 (first record 1902, latest revision 2013).
  • Of 2 revisions whose previous recommendation had an uncertainty, 1 (2013) put the new value outside the previous (expanded) range.
  • The current standard atomic weight is 232.0377(4) (recommended in 2013).
0+10⁻⁵−10⁻⁵+10⁻⁴−10⁻⁴+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
1902232.5no uncertaintyO=16232.4912812510.1007/BF01370337
1909232.42no uncertaintyO=16232.4112842510.1021/ja01931a001
1911232.4no uncertaintyO=16232.39128510.1021/ja01928a001
1920232.15no uncertaintyO=16232.1412943810.1021/ja02233a600
1931232.12no uncertaintyO=16232.111295510.1039/JR9310001617
1953232.05no uncertaintyO=16232.0412981210.1039/JR9540004713
1961232.038no uncertainty12C=12232.03810.1021/ja00881a001
1969232.0381(1)value(uncertainty)12C=12232.038110.1351/pac197021010091
2005232.038 06(2)value(uncertainty)12C=12232.03806−0.40010.1351/pac200678112051
2013232.0377(4)value(uncertainty)12C=12232.0377−18.00010.1515/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