Project Details The constitution of group 3 of the periodic table

Project No.: 
Start Date: 
18 December 2015
End Date: 
31 December 2021


This project will deliver a recommendation in favor of the composition of group 3 of the periodic table as consisting either of

  1. the elements Sc, Y, Lu and Lr, or
  2. the elements Sc, Y, La and Ac.

The task group does not intend to recommend the use of a 32-column periodic table or an 18-column. This choice which is a matter of convention, rather than a scientific one, should be left to individual authors and educators. The task group will only concern itselve with the constitution of group 3. Once this is established, one is free to represent the periodic table in an 18 or 32 column format.


The question of precisely which elements should be placed in group 3 of the periodic table has been debated from time to time with apparently no resolution up to this point. This question has also received a recent impetus from several science news articles following an article in Nature magazine in which the measurement of the ionization energy of the element lawrencium was reported for the first time.

We believe that this question is of considerable importance for chemists, physicists as well as students of the subject. Students and instructors are typically puzzled by the fact that published periodic tables show variation in the way that group 3 of the periodic table is displayed. The aim of the project is to assemble a task group to make a recommendation to IUPAC regarding the membership of group 3 of the periodic table.

Various forms of evidence have been put forward in support of each version of group 3. In the basis of this evidence arguments have been proposed while appealing to chemical as well as physical properties, spectral characteristics of the elements and criteria concerning the electronic configurations of their atoms. The task force will aim to evaluate all this evidence in order to reach a conclusion that encompasses these different approaches.


March 2016 – Project announcement published in Chem. Int. March 2016, p. 22;

May 2017 update – The task group met at the 253rd National Meeting of the American Chemical Society, on April 2-6, 2017 in San Francisco, California. Various views were aired and the group is closer to making a recommendation to IUPAC.
An article titled “The group 3 dilemma” by Philip Ball (member of this task group) has appeared in a recent issue of the RSC magazine, Chemistry World (21 Apr 2017),

March 2018 update – An article titled “Rounding up lutetium” by Lars Öhrström has appeared Nature Chemistry 10, 372 (2018),

A book chapter titled ‘What Elements Belong to Group 3 ?’ by E. Scerri and W. Parsons, is published in ‘Mendeleev to Oganesson – A Multidisciplinary Perspective on the Periodic Table’ E. Scerri and G. Restrepo (eds), Oxford University Press, New York, 2018


Dec 2019 update – A survey of about 200 university textbooks of how group 3 of the periodic table has been prepared by UCLA student Jonathan Wong in association with Dr. Eric Scerri. The survey is divided into searches for each decade starting with the 1970s.  A final tab labeled “data” presents comparative graphs. > Access to google sheets


August 2020 update – Of relevance to this project is the recently published article by Scerri E. 2020 Recent attempts to change the periodic table. Phil. Trans. R. Soc. A 378: 20190300;


January 2021 update – The following article, “Provisional Report on Discussions on Group 3 of The Periodic Table” Chemistry International, vol. 43, no. 1, 2021, pp. 31-34. (; PDF) is intended as a brief progress report from this task group. It is also intended as a call for feedback or suggestions from members of IUPAC and other readers.

Page last updated 8 Apr 2021