The shape of the table is presented by Bohr effect of considering the properties of the elements as simple substances and for reactions to occur with the intervention of such substances. But for the study of compounds and reactions that occur between them, the key factor is the electron configurations of atoms in states of valence to them on the given compounds.
It follows that a more complete picture of the periodic table would be when you take into account the peculiarities of atoms in both its neutral state and in all its particular valence states. This is the proposal of Boris Nekrasov, a member of the Academy of Sciences in Moscow.
Nekrasov distinguishes three types of analogies between elements Total analogs are those in which the analogy is shown in all its valence, all analogs compared to the valence valences except for the group corresponding to the number that can be called characteristic and analogous to the valence characteristic .
Thus, in the table shown here distinguish the elements entirely analogous joined by continuous lines, such as Na and K.
Those analogies in all except the characteristic valences joined by dotted lines. This is the case of Na and Cu in both cases if you lose an electron (valence feature) your setup is different. In the first case is 8 (1s2, 2P6) and the second 18 (3s2, 3p6, 3d10).
Lastly presenting exclusively analogies carcetrística valence are connected with dashed lines. This is the case both S and Cr +6 elements have their valence electron configuration similar in the last layer 8 (2s2, 2p6) for the S and 8 (3s2, 3p6) for Cr.
The date 1930 is an educated guess: