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Atomic weight
U · uranium
우라늄
Takeaway
- Recommended or revised 10 times between 1902 and 2024 (first record 1902, latest revision 1999).
- Both revisions whose previous recommendation had an uncertainty kept the new value inside the previous (expanded) range.
- The current standard atomic weight is 238.028 91(3) (recommended in 1999).
| Yearyear of the recommendation | Value (as printed)as printed in CIAAW's table; digits in parentheses are the uncertainty (expanded range) in the last digits | Notationvalue(uncertainty), interval or no uncertainty | Scalebefore 1961 oxygen = 16, from 1961 ¹²C = 12 | Value, ¹²C scalepre-1961 values multiplied by 15.9994/16 | z vs previous(new − previous) ÷ previous uncertainty | ReportDOI of the CIAAW report |
|---|---|---|---|---|---|---|
| 1902 | 239.5 | no uncertainty | O=16 | 239.49101875 | 10.1007/BF01370337 | |
| 1903 | 238.5 | no uncertainty | O=16 | 238.49105625 | 10.1021/ja02003a001 | |
| 1916 | 238.2 | no uncertainty | O=16 | 238.1910675 | 10.1021/ja02176a001 | |
| 1925 | 238.17 | no uncertainty | O=16 | 238.16106862 | 10.1039/CT9252700913 | |
| 1931 | 238.14 | no uncertainty | O=16 | 238.13106975 | 10.1039/JR9310001617 | |
| 1937 | 238.07 | no uncertainty | O=16 | 238.06107238 | 10.1039/JR9370001900 | |
| 1961 | 238.03 | no uncertainty | 12C=12 | 238.03 | 10.1021/ja00881a001 | |
| 1969 | 238.029(1) | value(uncertainty) | 12C=12 | 238.029 | 10.1351/pac197021010091 | |
| 1979 | 238.0289(1) | value(uncertainty) | 12C=12 | 238.0289 | −0.100 | 10.1351/pac198052102349 |
| 1999 | 238.028 91(3) | value(uncertainty) | 12C=12 | 238.02891 | 0.100 | 10.1351/pac200173040667 |
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