Project Details The constitution of group 3 of the periodic table

Project No.:
Start Date:
18 December 2015
End Date:
Division Name:
Inorganic Chemistry Division
Division No.:


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;

The task group will meet next at the 253rd National Meeting of the American Chemical Society, on April 2-6, 2017 in San Francisco, California.

Page last updated 29 August 2016