Mathematical analysis could help answer where hydrogen or lanthanum should sit on the table
As Dmitri Mendeleev’s iconic periodic table celebrates its 150th anniversary this year, two researchers have tried to understand what its ‘periodicity’ really means. The term reflects the recurrence of chemical properties down the list of elements, but even today ambiguities and arguments about the best way to represent those regularities in the table remain. Wilmer Leal and Guillermo Restrepo of the Max Planck Institute for Mathematics in the Sciences in Leipzig, Germany, hope that their mathematical analysis of the formal structure of ‘periodic systems’ like this might help to resolve some of those disputes.