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Atomic weight
Si · silicon
규소
Takeaway
- Recommended or revised 9 times between 1902 and 2024 (first record 1902, latest revision 2009).
- Both revisions whose previous recommendation had an uncertainty kept the new value inside the previous (expanded) range.
- Since 2009, it has been given as the interval [28.084, 28.086] rather than a single value (the range found in normal materials).
| 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 | 28.4 | no uncertainty | O=16 | 28.398935 | 10.1007/BF01370337 | |
| 1909 | 28.3 | no uncertainty | O=16 | 28.29893875 | 10.1021/ja01931a001 | |
| 1922 | 28.1 | no uncertainty | O=16 | 28.09894625 | 10.1021/ja01441a001 | |
| 1925 | 28.06 | no uncertainty | O=16 | 28.05894775 | 10.1039/CT9252700913 | |
| 1951 | 28.09 | no uncertainty | O=16 | 28.08894662 | 10.1039/JR9530000001 | |
| 1961 | 28.086(1) | value(uncertainty) | 12C=12 | 28.086 | 10.1021/ja00881a001 | |
| 1969 | 28.086(3) | value(uncertainty) | 12C=12 | 28.086 | 0.000 | 10.1351/pac197021010091 |
| 1975 | 28.0855(3) | value(uncertainty) | 12C=12 | 28.0855 | −0.167 | 10.1351/pac197647010075 |
| 2009 | [28.084, 28.086] | interval | 12C=12 | 28.085 (interval midpoint, for calculation) | 10.1351/PAC-REP-10-09-14 |
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