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Atomic weight
Pa · protactinium
프로트악티늄
Takeaway
- Recommended or revised 6 times between 1902 and 2024 (first record 1936, latest revision 2017).
- Both revisions whose previous recommendation had an uncertainty kept the new value inside the previous (expanded) range.
- The current standard atomic weight is 231.035 88(1) (recommended in 2017).
| 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 |
|---|---|---|---|---|---|---|
| 1936 | 231 | no uncertainty | O=16 | 230.9913375 | 10.1039/JR9370001893 | |
| 1969 | 231.0359(1) | value(uncertainty) | 12C=12 | 231.0359 | 10.1351/pac197021010091 | |
| 1985 | 231.035 88(2) | value(uncertainty) | 12C=12 | 231.03588 | −0.200 | 10.1351/pac198658121677 |
| 1987 | n/a | withdrawn | 12C=12 | 10.1351/pac198860060841 | ||
| 1989 | 231.035 88(2) | value(uncertainty) | 12C=12 | 231.03588 | 10.1351/pac199163070975 | |
| 2017 | 231.035 88(1) | value(uncertainty) | 12C=12 | 231.03588 | 0.000 | 10.1515/pac-2019-0603 |
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