Eu · europium

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Takeaway

Recommended or revised 6 times between 1902 and 2024 (first record 1902, latest revision 1995).
Both revisions whose previous recommendation had an uncertainty kept the new value inside the previous (expanded) range.
The current standard atomic weight is 151.964(1) (recommended in 1995).

Relative deviation from the current (or last) value, symmetric-log axis. Bars: uncertainty (expanded range); open circles: no uncertainty; orange boxes: intervals.

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	152	no uncertainty	O=16	151.9943		10.1007/BF01370337
1909	152.0	no uncertainty	O=16	151.9943		10.1021/ja01931a001
1961	151.96	no uncertainty	12C=12	151.96		10.1021/ja00881a001
1969	151.96(1)	value(uncertainty)	12C=12	151.96		10.1351/pac197021010091
1985	151.965(9)	value(uncertainty)	12C=12	151.965	0.500	10.1351/pac198658121677
1995	151.964(1)	value(uncertainty)	12C=12	151.964	−0.111	10.1351/pac199668122339

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