I would like to start by quoting Dmitri Mendeleev’s ‘The Relations between the Properties of Elements and Their Atomic Weights:
’…every (periodic) system, however, that is based upon exactly observed numbers is to be preferred of course to other systems not based upon numbers because then only little margin is left to arbitrariness… Properties, such as the optical and even the electrical or magnetic ones, cannot serve as basis for the system naturally, since one and the same body, according to the state in which it happens to be at the moment, may show enormous differences in this regard.’

Today’s standard IUPAC Periodic Table does not follow the quantum numbers n, l, ml and ms, which define electronic configurations of the atoms, which, in turn, define nature of the elements. When attempt was made to bring the traditional Periodic Table in conformance with the quantum numbers (ADOMAH Periodic Table) unexpected results have occurred:

the fdps blocks of the Periodic Table are happened to be equally spaced slices of the regular tetrahedron! Dmitri Mendeleev was right!