News & Notices
Standard Atomic Weights Revised
The Commission on Isotopic
Abundances and Atomic Weights (II.1) met for two days, on 10-11
August 2005, during the 43rd IUPAC General Assembly in Beijing. Following
its meeting, the Commission released the changes to the standard atomic
weights, Ar(E), of 16 chemical elements. The following
changes are based on new determinations of isotopic abundances and reviews
of previous isotopic abundances and atomic masses:
|
From |
To |
Aluminium |
26.981
538 (2) |
26.981
5386 (8) |
Bismuth |
208.980
38 (2) |
208.980
40 (1) |
Caesium |
132.905
45 (2) |
132.905
4519 (2) |
Cobalt |
58.933
200 (9) |
58.933
195 (5) |
Gold |
196.966
55 (2) |
196.966
569 (4) |
Lanthanum |
138.9055
(2) |
138.905
47 (7) |
Manganese |
54.938
049 (9) |
54.938
045 (5) |
Neodymium |
144.24
(3)
|
144.242
(3) |
Phosphorus |
30.973
761 (2) |
30.973
762 (2) |
Platinum |
195.078
(2)
|
195.084
(9) |
Samarium |
150.36
(3)
|
150.36
(2) |
Scandium |
44.955
910 (8) |
44.955
912 (6) |
Sodium |
22.989
770 (2) |
22.989
769 28 (2) |
Tantalum |
180.9479
(1)
|
180.947
88 (2) |
Terbium |
158.925
34 (2) |
158.925
35 (2) |
Thorium |
232.0381
(1) |
232.038
06 (2) |
The values are
presented in a concise notation whereby the standard uncertainty is
given in parenthesis next to the least significant digits to which
it applies; for example, Ar(Al) = 26.981 538 (2)
is the concise form of the expression Ar(Al) = 26.981 538 ± 0.000 002
These changes in the atomic weights will be published in a new Table
of Standard Atomic Weights 2005, which will be submitted for publication
in Pure and Applied Chemistry* by the end of 2005. The commission
also continued its review of publications of variations in the natural
isotopic abundances. For more details about the Commission meeting in
Beijing, see Chem.
Int.
Nov/Dec 2005 issue, Division Roundups on p. 7, or contact Michael
E. Wieser <[email protected]>,
secretary of the Commission.
first posted 19 Oct
05
* IUPAC Technical
Report published as Pure
Appl. Chem.
78(11), 2051-2066, 2006
<release published in Chem.
Int.
Nov/Dec 2005 issue>
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