Title: The Table of Standard Atomic Weights—an exercise in consensus

Abstract

The present Table of Standard Atomic Weights (TSAW) of the elements is perhaps one of the most familiar datasets in science. Unlike most parameters in physical science whose values and uncertainties are evaluated using the “Guidelines for Uncertainty in Measurement” (GUM), the majority of standard atomic-weight values and their uncertainties are consensus values, not GUM-evaluated values. The Commission on Isotopic Abundances and Atomic Weights of the International Union of Pure and Applied Chemistry (IUPAC) regularly evaluates the literature for new isotopic-abundance measurements that can lead to revised standard atomic-weight values, A _r(E) for element E. The Commission strives to provide utmost clarity in products it disseminates, namely the TSAW and the Table of Isotopic Compositions of the Elements (TICE). In 2016, it was recognized by the Commission that a guideline recommending expression of uncertainty listed in parentheses following the standard atomic-weight value, e.g. A _r (Se) = 78.971(8), is not in accord with the GUM, which suggests that this parenthetic notation be reserved to express standard uncertainty, not the expanded uncertainty used in the TSAW and TICE. In 2017, to eliminate this noncompliance with the GUM, a new format was adopted in which the uncertainty value is specified by themore » plus-minus symbol, e.g. A _r (Se) = 78.971 ± 0.008. To clarify the definition of uncertainty, a new footnote has been added to the TSAW. This footnote emphasizes that an atomic-weight uncertainty is a consensus (decisional) uncertainty. Not only has the Commission shielded users of the TSAW and TICE from unreliable measurements that appear in the literature as a result of unduly small uncertainties, but the aim of IUPAC has been fulfilled by which any scientist, taking any natural sample from commerce or research, can expect their sample atomic weight to lie within A _r(E) ± its uncertainty almost all of the time.« less

Authors:

Coplen, Tyler B.  ^[1];

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Holden, Norman E.  ^[2];

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Ding, Tiping  ^[3];

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Meijer, Harro A. J.  ^[4];

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• Search DOE PAGES for ORCID "0000-0001-8744-5632"

Vogl, Jochen  ^[5];

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Zhu, Xiangkun  ^[6]

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• Search DOE PAGES for ORCID "0000-0002-8407-6883"

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+ Show Author Affiliations

1. U.S. Geological Survey, Reston, VA (United States)
2. Brookhaven National Lab. (BNL), Upton, NY (United States)
3. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Mineral Resources
4. Univ. of Groningen (The Netherlands). Centre for Isotope Research (CIO)
5. Bundesanstalt für Materialforschung und ‐prüfung (BAM), Berlin (Germany)
6. Chinese Academy of Geological Sciences, Beijing (China). Inst. of Geology

Publication Date:

Fri Jun 19 00:00:00 EDT 2020

Research Org.:

Brookhaven National Lab. (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Nuclear Physics (NP)

OSTI Identifier:

1618411

Report Number(s):

BNL-215913-2020-JAAM
Journal ID: ISSN 0951-4198

Grant/Contract Number:  

SC0012704

Resource Type:

Accepted Manuscript

Journal Name:

Rapid Communications in Mass Spectrometry

Additional Journal Information:

Journal Volume: 36; Journal Issue: 15; Journal ID: ISSN 0951-4198

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

73 NUCLEAR PHYSICS AND RADIATION PHYSICS; decisional uncertainty; normal materials; conventional atomic weight; TSAW; TICE