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The INTERNET Database of Periodic Tables

There are thousands of periodic tables in web space, but this is the only comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Mark R. Leach Ph.D.

Use the drop menus below to search & select from the more than 1100 Period Tables in the database:

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Periodic Tables from the year 1936:

1936   Nekrasov Periodic Table
1936   Orbital Filling
1936   Libedinski's Periodic Classification of The Elements


Nekrasov Periodic Table

From here, using Google Translate:

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 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.

Thanks to Eric Scerri for the tip!
See the website and Eric's Twitter Feed.

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Orbital Filling With Electrons

Students of chemistry are often confused why the orbitals fill with electrons: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6... etc., because the 3d10 seems to be 'out of sequence'.

This 'out of sequence' difficulity is nicely explained if the orbitals are arranged in a slightly different way:

The aufbau principle states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels. For example, the 1s shell is filled before the 2s subshell is occupied. In this way, the electrons of an atom or ion form the most stable electron configuration possible.

The order in which these orbitals are filled is given by the n + rule, also known as the Madelung rule (after Erwin Madelung), the Janet rule or the diagonal rule.

Orbitals with a lower n + value are filled before those with higher n + values. In this context, n represents the principal quantum number and ? the azimuthal quantum number. The values = 0, 1, 2, 3 correspond to the s, p, d and f orbital lables.

Julio Gutiérrez Samanez writes:

"I send you the diagram below that reconciles quantum mechanics (diagram for filling the electronic cells) with the Janet table or LSPT. Explaining the duplication of periods with the duplication of the quantum number n, and the introduction of Tao (T) spin of the level or spin of the period, which explains the parity of the symmetric periods."

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Libedinski's Periodic Classification of The Elements

Simón Libedinski: PERIODIC CLASSIFICATION OF THE ELEMENTS, from his book: Dialectical Materialism, in Nature, in Society and in Medicine, Ediciones Ercilla, Santiago de Chile, 1938, pp 56-57:

"Mendeleev's Table, like that of Werner and others, are not, however, more than flat projections of the actual ordering of the elements. There is as much difference between Mendeleev's Table and the real group as there is between the planisphere and a rotating globe. A rational representation, starting from the simplest element – the negative electron –, would be a spiral line that, surrounding said central point, first gave a small turn, touching only two bodies: hydrogen and helium. From here it would jump to a much larger orbit, in which it would touch eight bodies and then another equal, also of eight. From here, another jump to a much larger orbit, comprising eighteen bodies, and then another equal; from this point one jumps to another orbit, again augmented, comprising thirty-two bodies (including rare earths); and when this round is over, the last one begins, to vanish a short distance.

"In the dialectical grouping of the elements, which I have the satisfaction of exposing, the classic arrangement of the same is respected. Only the arrangement changes, which instead of being rectilinear, is spiral. So I managed to suppress the anomaly of the double columns, and comfortably incorporate the important group of rare earths. I can not give my graphic the name of Tabla, because it is just the opposite: it aims to give the idea of ??space, and of movement in space. The double columns of the Classic Table can be found here as well, but only if you look through the whole, considered as a planetary system of conical shape, with the electron at the vertex. Effectively: column 1 coincides, through space, with column 1a; column 4 with column 4 bis, etc. The dialectical grouping also allows us to easily appreciate the remarkable dialectical character of the properties of matter: these properties are repeated periodically. These are the "returns" to qualities or previous properties, but not exactly equal to those, but only similar: and this resemblance, only to a certain extent. The difference is that that quality, those properties or some characteristic, are exalted to each dialectical return."

Contributed by Julio Antonio Gutiérrez Samanez, Cusco, Peru, March 2018 (using Google Translation)

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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