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Commission on Isotopic Abundances and Atomic Weights

November 12, 2023

The Commission on Isotopic Abundances and Atomic Weights (CIAAW) is an international scientific committee of the International Union of Pure and Applied Chemistry (IUPAC) under its Division of Inorganic Chemistry. Since 1899, it is entrusted with periodic critical evaluation of atomic weights of chemical elements and other cognate data, such as the isotopic composition of elements.[1] The biennial CIAAW Standard Atomic Weights are accepted as the authoritative source in science and appear worldwide on the periodic table wall charts.[2]

Commission on Isotopic Abundances and Atomic Weights
AbbreviationCIAAW
Formation1899; 124 years ago (1899)
TypeInternational scientific organization
PurposeTo provide internationally recommended values of isotopic composition and atomic weights of elements
Region served
Worldwide
Official language
English
Chair
Johanna Irrgeher
Secretary
Jochen Vogl
Parent organization
IUPAC (since 1920)
Websitewww.ciaaw.org

The use of CIAAW Standard Atomic Weights is also required legally, for example, in calculation of calorific value of natural gas (ISO 6976:1995), or in gravimetric preparation of primary reference standards in gas analysis (ISO 6142:2006). In addition, until 2019 the definition of kelvin, the SI unit for thermodynamic temperature, made direct reference to the isotopic composition of oxygen and hydrogen as recommended by CIAAW.[3] The latest CIAAW report was published on May 2022.[4]

Establishment edit

 
 
The inaugural members of the International Committee on Atomic Weights were:

Although the atomic weight had taken on the concept of a constant of nature like the speed of light, the lack of agreement on accepted values created difficulties in trade. Quantities measured by chemical analysis were not being translated into weights in the same way by all parties and standardization became an urgent matter.[5] With so many different values being reported, the American Chemical Society (ACS), in 1892, appointed a permanent committee to report on a standard table of atomic weights for acceptance by the Society. Clarke, who was then the chief chemist for the U.S. Geological Survey, was appointed a committee of one to provide the report. He presented the first report at the 1893 annual meeting and published it in January 1894.[6]

In 1897, the German Society of Chemistry, following a proposal by Hermann Emil Fischer, appointed a three-person working committee to report on atomic weights. The committee consisted of Chairman Prof. Hans H. Landolt (Berlin University), Prof. Wilhelm Ostwald (University of Leipzig), and Prof. Karl Seubert (University of Hanover). This committee published its first report in 1898, in which the committee suggested the desirability of an international committee on atomic weights. On 30 March 1899 Landolt, Ostwald and Seubert issued an invitation to other national scientific organizations to appoint delegates to the International Committee on Atomic Weights. Fifty-eight members were appointed to the Great International Committee on Atomic Weights, including Frank W. Clarke.[7] The large committee conducted its business by correspondence to Landolt which created difficulties and delays associated with correspondence among fifty-eight members. As a result, on 15 December 1899, the German committee asked the International members to select a small committee of three to four members.[8] In 1902, Prof. Frank W. Clarke (USA), Prof. Karl Seubert (Germany), and Prof. Thomas Edward Thorpe (UK) were elected, and the International Committee on Atomic Weights published its inaugural report in 1903 under the chairmanship of Prof. Clarke.[9]

Function edit

Since 1899, the Commission periodically and critically evaluates the published scientific literature and produces the Table of Standard Atomic Weights. In recent times, the Table of Standard Atomic Weights has been published biennially. Each recommended standard atomic-weight value reflects the best knowledge of evaluated, published data. In the recommendation of standard atomic weights, CIAAW generally does not attempt to estimate the average or composite isotopic composition of the Earth or of any subset of terrestrial materials. Instead, the Commission seeks to find a single value and symmetrical uncertainty that would include almost all substances likely to be encountered.[10]

Notable decisions edit

Many notable decisions have been made by the Commission over its history. Some of these are highlighted below.

 
The inaugural 1903 report of the International Atomic Weights Commission

International atomic weight unit: H=1 or O=16 edit

Though Dalton proposed setting the atomic weight of hydrogen as unity in 1803, many other proposals were popular throughout the 19th century. By the end of the 19th century, two scales gained popular support: H=1 and O=16. This situation was undesired in science and in October 1899, the inaugural task of the International Commission on Atomic Weights was to decide on the international scale and the oxygen scale became the international standard.[11] The endorsement of the oxygen scale created significant backlash in the chemistry community, and the inaugural Atomic Weights Report was thus published using both scales. This practice soon ceded and the oxygen scale remained the international standard for decades to come. Nevertheless, when the Commission joined the IUPAC in 1920, it was asked to revert to the H=1 scale, which it rejected.

Modern unit: 12C=12 edit

With the discovery of oxygen isotopes in 1929, a situation arose where chemists based their calculations on the average atomic mass (atomic weight) of oxygen whereas physicists used the mass of the predominant isotope of oxygen, oxygen-16. This discrepancy became undesired and a unification between the chemistry and physics was necessary.[12] In the 1957 Paris meeting the Commission put forward a proposal for a carbon-12 scale.[13] The carbon-12 scale for atomic weights and nuclide masses was approved by IUPAP (1960) and IUPAC (1961) and it is still in use worldwide.[14]

Uncertainty of the atomic weights edit

In the early 20th century, measurements of the atomic weight of lead showed significant variations depending on the origin of the sample. These differences were considered to be an exception attributed to lead isotopes being products of the natural radioactive decay chains of uranium. In 1930s, however, Malcolm Dole reported that the atomic weight of oxygen in air was slightly different from that in water.[15] Soon thereafter, Alfred Nier reported natural variation in the isotopic composition of carbon. It was becoming clear that atomic weights are not constants of nature. At the Commission’s meeting in 1951, it was recognized that the isotopic-abundance variation of sulfur had a significant effect on the internationally accepted value of an atomic weight. In order to indicate the span of atomic-weight values that may apply to sulfur from different natural sources, the value ± 0.003 was attached to the atomic weight of sulfur. By 1969, the Commission had assigned uncertainties to all atomic-weight values.

 
Excerpt of the IUPAC Periodic Table of the Elements 2011 showing the interval notation of the standard atomic weights of boron, carbon, and nitrogen

Interval notation edit

At its meeting in 2009 in Vienna, the Commission decided to express the standard atomic weight of hydrogen, carbon, oxygen, and other elements in a manner that clearly indicates that the values are not constants of nature.[16][17] For example, writing the standard atomic weight of hydrogen as [1.007 84, 1.008 11] shows that the atomic weight in any normal material will be greater than or equal to 1.007 84 and will be less than or equal to 1.008 11.[18]

Affiliations and name edit

The Commission on Isotopic Abundances and Atomic Weights has undergone many name changes:

  • The Great International Committee on Atomic Weights (1899-1902)
  • International Committee on Atomic Weights (1902-1920)
  • IUPAC Commission on Atomic Weights (1920-1922)
  • IUPAC Commission on Chemical Elements (1922-1930)
  • IUPAC Commission on Atomic Weights (1930-1979)
  • IUPAC Commission of Atomic Weights and Isotopic Abundances (1979-2002)
  • IUPAC Commission of Isotopic Abundances and Atomic Weights (2002–present)

Notable members edit

 
The Harvard chemist Theodore W. Richards, a member of the International Atomic Weights Commission, was awarded the 1914 Nobel Prize in Chemistry for his work on atomic weight determination

Since its establishment, many notable chemists have been members of the Commission. Notably, eight Nobel laureates have served in the Commission: Henri Moissan (1903-1907), Wilhelm Ostwald (1906-1916), Francis William Aston, Frederick Soddy, Theodore William Richards, Niels Bohr, Otto Hahn and Marie Curie.

Richards was awarded the 1914 Nobel Prize in Chemistry "in recognition of his accurate determinations of the atomic weight of a large number of chemical elements"[19] while he was a member of the Commission.[20] Likewise, Francis Aston was a member of the Commission when he was awarded the 1922 Nobel Prize in Chemistry for his work on isotope measurements.[21] Incidentally, the 1925 Atomic Weights report was signed by three Nobel laureates.[22]

Among other notable scientists who have served on the Commission were Georges Urbain (discoverer of lutetium, though priority was disputed with Carl Auer von Welsbach), André-Louis Debierne (discoverer of actinium, though priority has been disputed with Friedrich Oskar Giesel), Marguerite Perey (discoverer of francium), Georgy Flyorov (namesake of the element flerovium),[23] Robert Whytlaw-Gray (first isolated radon), and Arne Ölander (Secretary and Member of the Nobel Committee for Chemistry).

Chairs of the Commission edit

Since its establishment, the chairs of the Commission have been:

In 1950, the Spanish chemist Enrique Moles became the first Secretary of the Commission when this position was created.

See also edit

References edit

  1. ^ "Nobel Prize in Chemistry 1914 - Presentation". Nobelprize.org. November 11, 1915. from the original on June 30, 2017.
  2. ^ "IUPAC, Oxford Reference". from the original on 2013-09-22. {{cite journal}}: Cite journal requires |journal= (help)
  3. ^ "Clarification of the definition of the kelvin, unit of thermodynamic temperature" (PDF). BIPM. 2005. (PDF) from the original on 2013-06-26.
  4. ^ Thomas Prohaska; Johanna Irrgeher; Jacqueline Benefield; John Karl Boehlke; Lesley Chesson; Tyler B Coplen; Tiping Ding; Philip J H Dunn; Manfred Gröning; Norman E Holden; Harro A J Meijer; Heiko Moossen; Antonio Possolo; Yoshio Takahashi; Jochen Vogl; Thomas Walczyk; Jun Wang; Michael Wieser; Shigekazu Yoneda; Xiangkun Zhu; Juris Meija (2022). "Standard Atomic weights of the elements 2021 (IUPAC Technical Report)". Pure Appl. Chem. 94 (5): 573–600. doi:10.1515/pac-2019-0603.
  5. ^ E. Crawford (1992). Nationalism and Internationalism in Science, 1880-1939 (p.40). Cambridge University Press. ISBN 9780521524742. from the original on 2016-05-09.
  6. ^ "Atomic Weights and the International Committee—A Historical Review". Chemistry International. 2004. from the original on 2017-07-09.
  7. ^ L.M. Dennis, Frank Wigglesworth Clarke (National Academy of Sciences 1932) at p.143 2012-10-15 at the Wayback Machine
  8. ^ H. Landolt; W. Ostwald; K. Seubert (1900). "Zweiter Bericht der Commission für die Festsetzung der Atomgewichte". Ber. 22 (2): 1847–1883. doi:10.1002/cber.19000330270.
  9. ^ F.W. Clarke (1903). "Report of the International Committee on Atomic Weights". J. Am. Chem. Soc. 25 (1): 1–5. doi:10.1021/ja02003a001.
  10. ^ Michael E. Wieser; Michael Berglund (2009). "Atomic weights of the elements 2007 (IUPAC Technical Report)" (PDF). Pure Appl. Chem. 81 (11): 2131–2156. CiteSeerX 10.1.1.540.9258. doi:10.1351/PAC-REP-09-08-03. S2CID 98084907. (PDF) from the original on 2016-03-04.
  11. ^ Richards, Theodore William (1900). "International Atomic Weights". Proceedings of the American Academy of Arts and Sciences. 36 (10): 171–176. doi:10.2307/20020992. JSTOR 20020992.
  12. ^ F.W. Aston (1931). "The Unit of Atomic Weight". Nature. 128 (3234): 731. Bibcode:1931Natur.128..731.. doi:10.1038/128731a0. S2CID 4134425.
  13. ^ Edward Wichers (1958). "Report on Atomic Weights for 1956-1957". J. Am. Chem. Soc. 80 (16): 4121–4124. doi:10.1021/ja01549a001.
  14. ^ Encyclopædia Britannica 2013-03-08 at the Wayback Machine
  15. ^ Malcolm Dole (1935). "The Relative Atomic Weight of Oxygen in Water and in Air". J. Am. Chem. Soc. 57 (12): 2731. doi:10.1021/ja01315a511.
  16. ^ "Mass Migration: Chemists Revise Atomic Weights of 10 Elements". Scientific American. 16 December 2010. from the original on 30 December 2011.
  17. ^ "Atomic weights change to reflect natural variations". Chemistry World. 2010. from the original on 2013-09-23.
  18. ^ Tyler B. Coplen; Norman E. Holden (2011). "Atomic Weights: No Longer Constants of Nature". Chemistry International. from the original on 2013-06-14.
  19. ^ "The Nobel Prize in Chemistry 1914". from the original on 2017-06-29.
  20. ^ "Nobel Prize for Richards; Chemistry Award for 1914 Goes to the Harvard Investigator". The New York Times. 13 Nov 1915. from the original on 2013-09-22.
  21. ^ F.W. Aston; et al. (1923). "Report of the International Committee on Chemical Elements: 1923". J. Am. Chem. Soc. 45 (4): 867–874. doi:10.1021/ja01657a001.
  22. ^ F.W. Aston; et al. (1925). "International Atomic Weights 1925". J. Am. Chem. Soc. 47 (3): 597–601. doi:10.1021/ja01680a001.
  23. ^ "Past and Current Membership Summary, CIAAW". from the original on 2014-10-15.

External links edit

  • Official website
  • Standard Atomic weights of the elements 2021 (IUPAC Technical Report)
  • Atomic weights of the elements 2013 (IUPAC Technical Report)
  • Isotopic compositions of the elements 2013 (IUPAC Technical Report)
  • Isotopic compositions of the elements 2009 (IUPAC Technical Report)

November 12, 2023
commission, isotopic, abundances, atomic, weights, ciaaw, international, scientific, committee, international, union, pure, applied, chemistry, iupac, under, division, inorganic, chemistry, since, 1899, entrusted, with, periodic, critical, evaluation, atomic, . The Commission on Isotopic Abundances and Atomic Weights CIAAW is an international scientific committee of the International Union of Pure and Applied Chemistry IUPAC under its Division of Inorganic Chemistry Since 1899 it is entrusted with periodic critical evaluation of atomic weights of chemical elements and other cognate data such as the isotopic composition of elements 1 The biennial CIAAW Standard Atomic Weights are accepted as the authoritative source in science and appear worldwide on the periodic table wall charts 2 Commission on Isotopic Abundances and Atomic WeightsAbbreviationCIAAWFormation1899 124 years ago 1899 TypeInternational scientific organizationPurposeTo provide internationally recommended values of isotopic composition and atomic weights of elementsRegion servedWorldwideOfficial languageEnglishChairJohanna IrrgeherSecretaryJochen VoglParent organizationIUPAC since 1920 Websitewww wbr ciaaw wbr orgThe use of CIAAW Standard Atomic Weights is also required legally for example in calculation of calorific value of natural gas ISO 6976 1995 or in gravimetric preparation of primary reference standards in gas analysis ISO 6142 2006 In addition until 2019 the definition of kelvin the SI unit for thermodynamic temperature made direct reference to the isotopic composition of oxygen and hydrogen as recommended by CIAAW 3 The latest CIAAW report was published on May 2022 4 Contents 1 Establishment 2 Function 3 Notable decisions 3 1 International atomic weight unit H 1 or O 16 3 2 Modern unit 12C 12 3 3 Uncertainty of the atomic weights 3 4 Interval notation 4 Affiliations and name 5 Notable members 5 1 Chairs of the Commission 6 See also 7 References 8 External linksEstablishment edit nbsp nbsp The inaugural members of the International Committee on Atomic Weights were Frank W Clarke US shown on the left Sir Edward Thorpe UK shown on the right Karl Seubert Germany Although the atomic weight had taken on the concept of a constant of nature like the speed of light the lack of agreement on accepted values created difficulties in trade Quantities measured by chemical analysis were not being translated into weights in the same way by all parties and standardization became an urgent matter 5 With so many different values being reported the American Chemical Society ACS in 1892 appointed a permanent committee to report on a standard table of atomic weights for acceptance by the Society Clarke who was then the chief chemist for the U S Geological Survey was appointed a committee of one to provide the report He presented the first report at the 1893 annual meeting and published it in January 1894 6 In 1897 the German Society of Chemistry following a proposal by Hermann Emil Fischer appointed a three person working committee to report on atomic weights The committee consisted of Chairman Prof Hans H Landolt Berlin University Prof Wilhelm Ostwald University of Leipzig and Prof Karl Seubert University of Hanover This committee published its first report in 1898 in which the committee suggested the desirability of an international committee on atomic weights On 30 March 1899 Landolt Ostwald and Seubert issued an invitation to other national scientific organizations to appoint delegates to the International Committee on Atomic Weights Fifty eight members were appointed to the Great International Committee on Atomic Weights including Frank W Clarke 7 The large committee conducted its business by correspondence to Landolt which created difficulties and delays associated with correspondence among fifty eight members As a result on 15 December 1899 the German committee asked the International members to select a small committee of three to four members 8 In 1902 Prof Frank W Clarke USA Prof Karl Seubert Germany and Prof Thomas Edward Thorpe UK were elected and the International Committee on Atomic Weights published its inaugural report in 1903 under the chairmanship of Prof Clarke 9 Function editSince 1899 the Commission periodically and critically evaluates the published scientific literature and produces the Table of Standard Atomic Weights In recent times the Table of Standard Atomic Weights has been published biennially Each recommended standard atomic weight value reflects the best knowledge of evaluated published data In the recommendation of standard atomic weights CIAAW generally does not attempt to estimate the average or composite isotopic composition of the Earth or of any subset of terrestrial materials Instead the Commission seeks to find a single value and symmetrical uncertainty that would include almost all substances likely to be encountered 10 Notable decisions editMany notable decisions have been made by the Commission over its history Some of these are highlighted below nbsp The inaugural 1903 report of the International Atomic Weights CommissionInternational atomic weight unit H 1 or O 16 edit Though Dalton proposed setting the atomic weight of hydrogen as unity in 1803 many other proposals were popular throughout the 19th century By the end of the 19th century two scales gained popular support H 1 and O 16 This situation was undesired in science and in October 1899 the inaugural task of the International Commission on Atomic Weights was to decide on the international scale and the oxygen scale became the international standard 11 The endorsement of the oxygen scale created significant backlash in the chemistry community and the inaugural Atomic Weights Report was thus published using both scales This practice soon ceded and the oxygen scale remained the international standard for decades to come Nevertheless when the Commission joined the IUPAC in 1920 it was asked to revert to the H 1 scale which it rejected Modern unit 12C 12 edit With the discovery of oxygen isotopes in 1929 a situation arose where chemists based their calculations on the average atomic mass atomic weight of oxygen whereas physicists used the mass of the predominant isotope of oxygen oxygen 16 This discrepancy became undesired and a unification between the chemistry and physics was necessary 12 In the 1957 Paris meeting the Commission put forward a proposal for a carbon 12 scale 13 The carbon 12 scale for atomic weights and nuclide masses was approved by IUPAP 1960 and IUPAC 1961 and it is still in use worldwide 14 Uncertainty of the atomic weights edit In the early 20th century measurements of the atomic weight of lead showed significant variations depending on the origin of the sample These differences were considered to be an exception attributed to lead isotopes being products of the natural radioactive decay chains of uranium In 1930s however Malcolm Dole reported that the atomic weight of oxygen in air was slightly different from that in water 15 Soon thereafter Alfred Nier reported natural variation in the isotopic composition of carbon It was becoming clear that atomic weights are not constants of nature At the Commission s meeting in 1951 it was recognized that the isotopic abundance variation of sulfur had a significant effect on the internationally accepted value of an atomic weight In order to indicate the span of atomic weight values that may apply to sulfur from different natural sources the value 0 003 was attached to the atomic weight of sulfur By 1969 the Commission had assigned uncertainties to all atomic weight values nbsp Excerpt of the IUPAC Periodic Table of the Elements 2011 showing the interval notation of the standard atomic weights of boron carbon and nitrogenInterval notation edit At its meeting in 2009 in Vienna the Commission decided to express the standard atomic weight of hydrogen carbon oxygen and other elements in a manner that clearly indicates that the values are not constants of nature 16 17 For example writing the standard atomic weight of hydrogen as 1 007 84 1 008 11 shows that the atomic weight in any normal material will be greater than or equal to 1 007 84 and will be less than or equal to 1 008 11 18 Affiliations and name editThis section does not cite any sources Please help improve this section by adding citations to reliable sources Unsourced material may be challenged and removed March 2018 Learn how and when to remove this template message International Union of Pure and Applied Chemistry IUPAC from 1920 International Association of Chemical Societies IACS from 1913 1919The Commission on Isotopic Abundances and Atomic Weights has undergone many name changes The Great International Committee on Atomic Weights 1899 1902 International Committee on Atomic Weights 1902 1920 IUPAC Commission on Atomic Weights 1920 1922 IUPAC Commission on Chemical Elements 1922 1930 IUPAC Commission on Atomic Weights 1930 1979 IUPAC Commission of Atomic Weights and Isotopic Abundances 1979 2002 IUPAC Commission of Isotopic Abundances and Atomic Weights 2002 present Notable members edit nbsp The Harvard chemist Theodore W Richards a member of the International Atomic Weights Commission was awarded the 1914 Nobel Prize in Chemistry for his work on atomic weight determinationSince its establishment many notable chemists have been members of the Commission Notably eight Nobel laureates have served in the Commission Henri Moissan 1903 1907 Wilhelm Ostwald 1906 1916 Francis William Aston Frederick Soddy Theodore William Richards Niels Bohr Otto Hahn and Marie Curie Richards was awarded the 1914 Nobel Prize in Chemistry in recognition of his accurate determinations of the atomic weight of a large number of chemical elements 19 while he was a member of the Commission 20 Likewise Francis Aston was a member of the Commission when he was awarded the 1922 Nobel Prize in Chemistry for his work on isotope measurements 21 Incidentally the 1925 Atomic Weights report was signed by three Nobel laureates 22 Among other notable scientists who have served on the Commission were Georges Urbain discoverer of lutetium though priority was disputed with Carl Auer von Welsbach Andre Louis Debierne discoverer of actinium though priority has been disputed with Friedrich Oskar Giesel Marguerite Perey discoverer of francium Georgy Flyorov namesake of the element flerovium 23 Robert Whytlaw Gray first isolated radon and Arne Olander Secretary and Member of the Nobel Committee for Chemistry Chairs of the Commission edit Since its establishment the chairs of the Commission have been Hans H Landolt nbsp 1899 1901 Frank W Clarke nbsp 1902 1921 Georges Urbain nbsp 1922 1929 Gregory P Baxter nbsp 1930 1949 Edward Wichers nbsp 1950 1959 Tomas Batuecas nbsp 1960 1963 Edward Wichers nbsp 1964 1969 Norman Greenwood nbsp 1970 1975 Etienne Roth nbsp 1976 1979 Norman E Holden nbsp 1980 1983 Raymond L Martin nbsp 1984 1987 John de Laeter nbsp 1988 1991 Klaus G Heumann nbsp 1992 1995 Ludolf Schultz nbsp 1996 2001 Philip Taylor nbsp 2002 2003 Tiping Ding nbsp 2004 2007 Roberto Gonfiantini nbsp 2008 2009 Willi A Brand nbsp 2010 2013 Juris Meija nbsp 2014 2021 Johanna Irrgeher nbsp 2022 present In 1950 the Spanish chemist Enrique Moles became the first Secretary of the Commission when this position was created See also editAtomic mass unit Committee on Data for Science and TechnologyReferences edit Nobel Prize in Chemistry 1914 Presentation Nobelprize org November 11 1915 Archived from the original on June 30 2017 IUPAC Oxford Reference Archived from the original on 2013 09 22 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Clarification of the definition of the kelvin unit of thermodynamic temperature PDF BIPM 2005 Archived PDF from the original on 2013 06 26 Thomas Prohaska Johanna Irrgeher Jacqueline Benefield John Karl Boehlke Lesley Chesson Tyler B Coplen Tiping Ding Philip J H Dunn Manfred Groning Norman E Holden Harro A J Meijer Heiko Moossen Antonio Possolo Yoshio Takahashi Jochen Vogl Thomas Walczyk Jun Wang Michael Wieser Shigekazu Yoneda Xiangkun Zhu Juris Meija 2022 Standard Atomic weights of the elements 2021 IUPAC Technical Report Pure Appl Chem 94 5 573 600 doi 10 1515 pac 2019 0603 E Crawford 1992 Nationalism and Internationalism in Science 1880 1939 p 40 Cambridge University Press ISBN 9780521524742 Archived from the original on 2016 05 09 Atomic Weights and the International Committee A Historical Review Chemistry International 2004 Archived from the original on 2017 07 09 L M Dennis Frank Wigglesworth Clarke National Academy of Sciences 1932 at p 143 Archived 2012 10 15 at the Wayback Machine H Landolt W Ostwald K Seubert 1900 Zweiter Bericht der Commission fur die Festsetzung der Atomgewichte Ber 22 2 1847 1883 doi 10 1002 cber 19000330270 F W Clarke 1903 Report of the International Committee on Atomic Weights J Am Chem Soc 25 1 1 5 doi 10 1021 ja02003a001 Michael E Wieser Michael Berglund 2009 Atomic weights of the elements 2007 IUPAC Technical Report PDF Pure Appl Chem 81 11 2131 2156 CiteSeerX 10 1 1 540 9258 doi 10 1351 PAC REP 09 08 03 S2CID 98084907 Archived PDF from the original on 2016 03 04 Richards Theodore William 1900 International Atomic Weights Proceedings of the American Academy of Arts and Sciences 36 10 171 176 doi 10 2307 20020992 JSTOR 20020992 F W Aston 1931 The Unit of Atomic Weight Nature 128 3234 731 Bibcode 1931Natur 128 731 doi 10 1038 128731a0 S2CID 4134425 Edward Wichers 1958 Report on Atomic Weights for 1956 1957 J Am Chem Soc 80 16 4121 4124 doi 10 1021 ja01549a001 Encyclopaedia Britannica Archived 2013 03 08 at the Wayback Machine Malcolm Dole 1935 The Relative Atomic Weight of Oxygen in Water and in Air J Am Chem Soc 57 12 2731 doi 10 1021 ja01315a511 Mass Migration Chemists Revise Atomic Weights of 10 Elements Scientific American 16 December 2010 Archived from the original on 30 December 2011 Atomic weights change to reflect natural variations Chemistry World 2010 Archived from the original on 2013 09 23 Tyler B Coplen Norman E Holden 2011 Atomic Weights No Longer Constants of Nature Chemistry International Archived from the original on 2013 06 14 The Nobel Prize in Chemistry 1914 Archived from the original on 2017 06 29 Nobel Prize for Richards Chemistry Award for 1914 Goes to the Harvard Investigator The New York Times 13 Nov 1915 Archived from the original on 2013 09 22 F W Aston et al 1923 Report of the International Committee on Chemical Elements 1923 J Am Chem Soc 45 4 867 874 doi 10 1021 ja01657a001 F W Aston et al 1925 International Atomic Weights 1925 J Am Chem Soc 47 3 597 601 doi 10 1021 ja01680a001 Past and Current Membership Summary CIAAW Archived from the original on 2014 10 15 External links editOfficial website Standard Atomic weights of the elements 2021 IUPAC Technical Report Atomic weights of the elements 2013 IUPAC Technical Report Isotopic compositions of the elements 2013 IUPAC Technical Report Isotopic compositions of the elements 2009 IUPAC Technical Report Retrieved from https en wikipedia org w index php title Commission on Isotopic Abundances and Atomic Weights amp oldid 1171990601, 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