Ca · calcium

칼슘

Takeaway

Recommended or revised 6 times between 1902 and 2024 (first record 1902, latest revision 1983).
The one revision whose previous recommendation had an uncertainty kept the new value inside the previous (expanded) range.
The current standard atomic weight is 40.078(4) (recommended in 1983).

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	40.1	no uncertainty	O=16	40.09849625		10.1007/BF01370337
1909	40.09	no uncertainty	O=16	40.08849662		10.1021/ja01931a001
1912	40.07	no uncertainty	O=16	40.06849738		10.1021/ja02224a601
1931	40.08	no uncertainty	O=16	40.078497		10.1039/JR9310001617
1969	40.08(1)	value(uncertainty)	12C=12	40.08		10.1351/pac197021010091
1983	40.078(4)	value(uncertainty)	12C=12	40.078	−0.200	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