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Atomic weight
K · potassium
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Takeaway
- Recommended or revised 11 times between 1902 and 2024 (first record 1902, latest revision 1979).
- Of 3 revisions whose previous recommendation had an uncertainty, 1 (1971) put the new value outside the previous (expanded) range.
- The current standard atomic weight is 39.0983(1) (recommended in 1979).
| 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 | 39.15 | no uncertainty | O=16 | 39.14853188 | 10.1007/BF01370337 | |
| 1909 | 39.10 | no uncertainty | O=16 | 39.09853375 | 10.1021/ja01931a001 | |
| 1925 | 39.096 | no uncertainty | O=16 | 39.0945339 | 10.1039/CT9252700913 | |
| 1931 | 39.10 | no uncertainty | O=16 | 39.09853375 | 10.1039/JR9310001617 | |
| 1934 | 39.096 | no uncertainty | O=16 | 39.0945339 | 10.1039/JR9340000499 | |
| 1951 | 39.100 | no uncertainty | O=16 | 39.09853375 | 10.1039/JR9530000001 | |
| 1961 | 39.102 | no uncertainty | 12C=12 | 39.102 | 10.1021/ja00881a001 | |
| 1969 | 39.102(3) | value(uncertainty) | 12C=12 | 39.102 | 10.1351/pac197021010091 | |
| 1971 | 39.098(3) | value(uncertainty) | 12C=12 | 39.098 | −1.333 | 10.1351/pac197230030637 |
| 1975 | 39.0983(3) | value(uncertainty) | 12C=12 | 39.0983 | 0.100 | 10.1351/pac197647010075 |
| 1979 | 39.0983(1) | value(uncertainty) | 12C=12 | 39.0983 | 0.000 | 10.1351/pac198052102349 |
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