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Atomic weightNo standard atomic weight (radioactive)
Ra · radium
라듐
Takeaway
- Recommended or revised 7 times between 1902 and 2024 (first record 1903, latest revision 1983).
- It has no standard atomic weight today: a radioactive element without a characteristic terrestrial isotopic composition.
| 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 |
|---|---|---|---|---|---|---|
| 1903 | 225 | no uncertainty | O=16 | 224.9915625 | 10.1021/ja02003a001 | |
| 1909 | 226.4 | no uncertainty | O=16 | 226.39151 | 10.1021/ja01931a001 | |
| 1925 | 225.95 | no uncertainty | O=16 | 225.94152688 | 10.1039/CT9252700913 | |
| 1931 | 225.97 | no uncertainty | O=16 | 225.96152612 | 10.1039/JR9310001617 | |
| 1936 | 226.05 | no uncertainty | O=16 | 226.04152312 | 10.1039/JR9370001893 | |
| 1969 | 226.0254(1) | value(uncertainty) | 12C=12 | 226.0254 | 10.1351/pac197021010091 | |
| 1983 | n/a | withdrawn | 12C=12 | 10.1351/pac198456060653 |
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