Project Details Machine-Accessible Periodic Table

Project No.:
Start Date:
17 December 2019
End Date:


Current standard atomic weights, nuclide masses, and isotopic abundances are openly available in a tabular and searchable format on the website of the IUPAC Commission on Isotopic Abundances and Atomic Weights While most of the CIAAW data are now available through this website, it is aimed to be human-readable and not machine-readable. This joint project between CIAAW and the Committee on Publications and Cheminformatics Data Standards (CPCDS) is to revise the data management practices for and to also make its data machine readable and richly annotated to enable accurate dissemination in chemical computer systems and to further adhere to the FAIR Data Principles.[1] Best practices and technical documentation are also needed to enable accurate utilization of isotopic abundance and atomic weight information.

[1] Wilkinson, M. D. et al. (2016). The FAIR Guiding Principles for Scientific Data Management and Stewardship. Nature Scientific Data 3, 160018.


In 2009, the CIAAW launched a project 2009-026-2-200 to facilitate and streamline the management of isotope data as used by IUPAC and CIAAW during data evaluation and provide customized isotope related output. The online database was deemed necessary to improve the speed and accuracy of the data evaluation, retain historical information, justification to changes, and provide instant specific access to official IUPAC approved data for the user community worldwide. Over the last decade, much work has been accomplished towards addressing many of these aims. The current standard atomic weights, nuclide masses, and isotopic abundances are now available in a tabular and searchable format on, all historical standard atomic weights (from 1902) are available in a searchable form and so are the recommended isotopic abundances (from 1975), all IUPAC best measurements (from 1975), and doi links to all CIAAW official reports from 1902.

While the CIAAW has taken significant steps in the digital era, much work remains to be done to ensure these critically evaluated data adhere to the FAIR Data Principles to be Findable, Accessible, Interoperable and Re-usable for both human experts and machine systems. Machine-accessible data require that values and associated uncertainties and other descriptive information be consistently expressed in text-based formats that can be parsed without human interpretation or intervention. Standardizing and curating the metadata associated with the atomic weights and other standard data will support more accurate computation, maintain links to provenance, and highlight important dates and actions of the Commission, such as the best measurements for isotopic abundance. The project will aim to develop best practices for toolkit providers in machine processing of these data, augment CIAAW curation practices for digital dissemination, and engage the broader community, including Mass Spec vendors and other disciplines who reference these data in their systems, such as Geochemistry.

The project will work through a number of objectives, including:
• Create a web services page to host links to the machine-readable datafiles.
• Establish standard metadata and data formats for easy uptake of the CIAAW data by humans and machines.
• Expand and index the best measurement datafile in order to recognize and celebrate the individuals, Laboratories and Countries which contribute to advance the isotope ratio measurement science.
• Expand the data in all sections and index by adding DOI links to references.
• Review available information and determine best practices for reporting precision; uncertainty; reduced precision; not reporting uncertainty; monoisotopic vs. atomic weight
• Develop validation protocols and resources (suite of machine-readable precomputed values)


Page last update 17 Dec 2019