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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 1300 Period Tables in the database: 

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Year:  2022 PT id = 1252

Vernon's Yin Yang of The Periodic Table

René Vernon writes:

"I was prompted to [develop] this item after reading Eric Scerri's open access article: In Praise of Triads. The nub of Eric’s article is to argue for the LST on the grounds of triad regularity, first-row-anomaly regularity, and consistency with QM.

"It occurs to me that efforts to introduce more regularity to the PT invariably introduce new irregularities elsewhere. For example, as far as triad regularity goes, the left step table (LST) with He over Be introduces its own anomaly in that no element in period 1 (H, He) is part of a triad whereas this is not the case for all periods thereafter. In contrast, all periods of the traditional table have at least one element that is part of a triad.

"As far as QM goes, this tells us that there is a theoretical regularity to the PT. This regularity can be used to inform e.g. the LST, ADOMAH or Julio’s binodes. But such depictions do not reflect the factual relationships we see amongst the chemistry of the elements as well as is the case for the conventional form. A most obvious example is that the LST, while being more consistent with QM, disrupts the bottom-left to top-right trend in metallic to nonmetallic character seen in conventional tables.

(I must caveat that I'm referring to the chemistry of the elements in conditions regularly occurring on Earth. For example, it has been reported that under sufficiently high pressures the elements change their EN and electron configurations. If so, this suggests a need for a different table at high pressure.)

At this point, the chemistry educators enter the picture. They move the s-block to left. Helium is relocated over Ne on the basis of its nobility. (This could change if a few compounds of He were to be synthesized). Somewhat similarly, La was discovered well before Lu, so it ended up under Y, and most folks see no good reason to replace La with Lu. Sure, in the 32-column form, the result is a split d-block but the infrequency with which the 32-column form appears is such that most people are not bothered. The result is the conventional table.

Philosophically, while the n+l based LST might represent the most general form of table, the conventional table appears to currently represent the most pragmatic derivation for chemists and chemistry educators.

Since the PT is classification rather than theory, and there will thus always be hard cases at the boundaries, there will invariably be minor variations in the depiction of the conventional table with respect to e.g. the placement of H, the composition of group 3, or the length of the f block.

And there will always be tables such as MR that focus on particular perspectives of relationships among the the elements.

I’ve tried to sketch what's going in the attached image:"

Click to enlarge.

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What is the Periodic Table Showing? Periodicity

© Mark R. Leach Ph.D. 1999 –

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