Commission on Isotopic Abundances and Atomic Weights

Description

The Commission on Isotopic Abundances and Atomic Weights (CIAAW) is an international scientific committee of IUPAC under its Inorganic Chemistry Division. Since 1899, CIAAW is entrusted with periodic critical evaluation of atomic weights of elements and other cognate data, such as the isotopic composition of elements. CIAAW has been a part of IUPAC since the first General Assembly of IUPAC in 1920. Visit the Commission’s website ciaaw.org for more information.

Subcommittees and Commissions

• Subcommittee on Isotopic Abundance Measurements
• Subcommittee on Stable Isotope Reference Material Assessment
• Subcommittee on Natural Assessment of Fundamental Understanding of Isotopes

Current Projects

• 2020-013-1-200 - Assessment of absolute isotope ratios for the international isotope delta measurement standards
• 2019-020-2-024 - Machine-Accessible Periodic Table
• 2019-024-1-200 - Statistical Models and Data Reductions to Estimate Standard Atomic Weights and Isotopic Ratios for the Elements, and to Evaluate the Associated Uncertainties
• 2017-023-2-200 - Collection, compilation and evaluation of elemental and isotopic data of calcium carbonate and hydroxyapatite materials
• 2017-017-2-200 - Evaluated Published Isotope Ratio Data (2013-2018)
• 2015-037-2-200 - IUPAC Molecular Weight Calculator
• 2014-016-2-200 - Compilation of the variation of the isotopic composition of the elements via crowdsourcing
• 2014-002-1-200 - Assessment of Stable Isotopic Reference Materials

Activity Reports

Recent releases and publications (full list is available at https://www.ciaaw.org/publications.htm)

• • 6 May 2021 – Standard atomic weight of lead revised based on the publication of the IUPAC Technical Report on the variation of lead isotopic composition and atomic weight in terrestrial materials (PAC, https://doi.org/10.1515/pac-2018-0916)
  • 11 December 2019 – CIAAW recommended changes to the standard atomic weight of hafnium based on recent determinations and evaluations of its isotopic composition
  • 5 June 2018 – CIAAW recommended changes to the standard atomic weights of 14 chemical elements: Al, Ar, Co, Au, Ho, Ir, Mn, Nb, Pr, Pa, Rh, Tb, Tm, and Y
  • 24 August 2015 – CIAAW recommended a change to the standard atomic weight of ytterbium
    –
  • ATOMIC WEIGHT
    – Atomic Weights of the Elements 2021, Pure Appl. Chem., 2022, Vol. 94, No. 5, pp. 573-600, https://doi.org/10.1515/pac-2019-0603
  • ISOTOPIC COMPOSITION
    – Isotopic Compositions of the Elements 2013, Pure Appl. Chem., 2016, Vol. 88, No. 3, pp. 293-306, https://doi.org/10.1515/pac-2015-0503
  • ELEMENT-BY-ELEMENT REVIEW
    – Atomic Weights of the Elements. Review 2000, Pure Appl. Chem., 2003, Vol. 75, No. 6, pp. 683-800, https://doi.org/10.1351/pac200375060683
  • NATURAL VARIATIONS OF ISOTOPIC COMPOSITION
    – Isotope-abundance variations and atomic weights of selected elements: 2016, Pure Appl. Chem., 2016, Vol. 88, No.12, pp. 1203-1224, https://doi.org/10.1515/pac-2016-0302
  • OTHER TECHNICAL REPORTS, historical reviews and educational publications
    see https://www.ciaaw.org/publications.htm
  • LINKS to
    – Periodic Table of the Elements (iupac.org/what-we-do)
    – Isotopesmatter.com (IUPAC project 2014-024-1-200)
    – IUPAC100 Periodic Table Challenge and Challenge 2.0
    – IYPT2019.org