tableau de Janet

CONT: Dans le tableau de Janet, on a deux périodes très courtes de deux éléments, au lieu d’une seule, avec le résultat que toutes les longueurs de période, sans exception, sont répétées.

CONT: Janet started from the fact that the series of chemical elements is a continuous sequence, which he represented as a helix traced on the surfaces of four nested cylinders. By various geometrical transformations he derived several striking designs, one of which is his ""left-step periodic table,"" in which hydrogen and helium are placed above lithium and beryllium. It was only later that he realized that his arrangement concorded perfectly with quantum theory and the electronic structure of the atom.