Thoughts on the periodic table

Eric Scerri has written the definitive history of Mendele’ev’s periodic table and how it came to be formulated. He also has a paper in which he proposes a new formulation, based on historical considerations of what it was that Mendele’ev was trying to do, and on more theoretical considerations of atomic number, not weight. Sciencebase discusses it here.

And of course, no post on the periodic table is complete without a link to Tom Lehrer’s “Elements” song. Here’s a fantastic version from YouTube:

[Hat tip: David Bradley]

26 thoughts on “Thoughts on the periodic table

  1. Thanks for the mention. This has turned out to be one of the most commented posts I’ve ever written with almost 200 responses back and forth from various people, chemists, and others chipping in with their thoughts on novel PTs, 2D, 3D, spiral, circular and other bizarre formats. Personally, I think the modern version of the 2D Mendeleev PT will stick for many years to come, despite 3D graphics.

       0 likes

  2. Thanks for the exposure.

    For those interested in this topic, namely the elements and the periodic table, see a recent BBC TV 4 documentary called,

    Chemistry A Volatile History which is available in 3 episodes on youtube. Each episode is in 6 parts.

    The treatment is a little elementary for experts but the visuals are wonderful and highly recommended.

    I was a consultant for episode 2 although they ignored many of my suggestions.

    all the best
    eric scerri

    And thanks to David bradley for his periodic table blog which is still up and running.

       0 likes

  3. I agree with David Bradley. There is little point in trying to devise 3-D and even higher dimensional periodic tables. The essential idea in the periodic system is that elements recur approximately every so often. In fact just to emphasize the point, I am currently developing some new one dimensional forms of the periodic table, such as a keyboard version in which elements in the same group are denoted by notes of the same color.

    all the best
    eric scerri

       0 likes

  4. I don’t think there have been any really new representations of the Periodic System since about 1950, though Tsimmerman’s Adomah PT gives added value to Janet’s LSPT, which surely is the best one. People just keep gnawing the same bones. The later chapters of Eric Scerri’s book are an excellent account of the underlying rationale, but for the history of the different graphic representations Van Spronsen’s 1969 book The Periodic System of Chemical Elements is still unrivalled. And I regret that people have come to use the expression ‘Periodic Table’ as a synonym for ‘Periodic System’. The system is more general and abstract than any of its representations, of which tables are only one class.

       0 likes

  5. Philip,
    thanks for your comment about Adomah Periodic Table.

    Periodic Table is naturally three dimensional because all elements are quantum systems defined by three whole quantum numbers n, l and ml. You can present PT in 2D, but its because we are used to seeing it on flat screens or sheets of paper.

       0 likes

  6. There is every reason to believe that an antimatter periodic table wouldn’t be entirely identical to the system for normal matter. Close, but no cigar, as they say.

    Prof. Scerri, Pascal numbers and alkaline earths? No relation to higher dimensions? Or relation but not worth depicting or mentioning?

    Jess Tauber

       0 likes

  7. The differences between the matter and anti-matter periodic systems might tell us something important about matter. Would positrons differ from electrons in their pattern of Aufbau, and if so how and why?

       0 likes

  8. Just to take a break from the question of how many dimensions should be used to represent the periodic system,

    take a look at the series of 3 BBC 4 TV programs called

    Chemistry : A Volatile History.

    also available on youtube.

    eric scerri

       0 likes

  9. Break in the break: has anyone considered FRACTAL dimensionalities for the PT? Heads spinning yet (+/- 1/2)?

    Jess Tauber

       0 likes

  10. The originator of these pages is John Wilkins a philosopher of biologist who has worked on classification.

    I wonder if we might get his views on chemical classification and whether he believes that there may be one best from of the periodic table which captures the correct grouping of elements, or whether he believes that the PT is a matter of convention and not worth agonizing over as Philip Stewart seems to be suggesting more and more.

    all the best,

    eric scerri

       0 likes

  11. I thought I had said that preference for a graphic representation (table or otherwise) is a matter of taste, not convention. But the Periodic System exists, and different representations can be faithful to different aspects of it. The most fundamental is electronic structure, and Janet was able to capture this in 1927, before he knew anything about quantum theory. I would say that any representation that does not respect the m+l rule has missed the main point. As Valery Tsimmerman has pointed out, there is an increase in m+l for the determining electron at the beginning of every ‘block’, irrespective of whether Aufbau is regular (cf La, Ac, Th). This therefore is a fundamental punctuation of the series.

       0 likes

  12. I am unable to make an informed comment, Eric, but I think it is something of a received myth that classifications in the absence of theory are mere conventions. I suspect this derives from a Carnapian Aufbau conception of scientific ontology. I am quite sure the PT is a representation of real phenomena, even when based on atomic weight.

       0 likes

  13. Thanks John,

    Let us also note in passing that there is a theory that provides an approximate explanation of the periodic table – it’s quantum mechanics, although one can quibble with how deductive this explanation really is.

    all the best
    eric scerri

       0 likes

    1. Of course, when I read your book I will be much better informed, but did QM get formulated in part because of the PT and subsequent developments based upon it?

      My claim will be, in my book on classification that I am planning with my friend Malte Ebach, that classifications can be made purely empirically, in a Hackingesque kind of way. Now, most are at least partially theoretical, but they need not be based on the theory for that domain of phenomena. They may precede there being one.

         0 likes

  14. If I am not mistaken, QM was needed to explain Spectroscopy more than PT. In fact QM is not necessary for PT formulation. Spectroscopy provide plenty of empirical data necessary for optimal PT construction, it clarified many aspects of Periodic System. In order to construct Left Step periodic system all is needed is Atomic Number Z and n+l rule, as I demonstrateted on my websites home page. Unfortunately, when chemists question role of QM in Periodic System, they also bundle it togeteher with Spectroscopy, that is purely empirical, and call it all “reduction of Chemistry to Physics”. Theory is nice but is not necessary for PT. Spectroscopy is.

    Valery Tsimmerman

       0 likes

  15. Charles Janet did not know quantum theory when he proposed the periodic table (and helix) that best rest represent it, and he later discovered the n+l rule from his work on his table. His procedure was simply to rearrange the long form of Mendeelev’s table (in its 1920s version) so as to make it perfectly regular. To do so he had to overcome his resistance to classifying helium with the alkaline earth metals. Actually there are irregularities of Aufbau that are not visible in his images, but that is part of what makes chemistry more than just an elaboration of physics.

       0 likes

  16. I wasn’t thinking in terms of QM either when I first delved into the tetrahedral morass- in fact hadn’t yet taken my QM course in undergrad school. I just noticed that if you stacked the spdf blocks vertically, and allowed for elements up to 120, that you got a tetrahedral arrangement in 3D, with the horizontal axis twice the length of the vertical. Then I discovered what Valery has termed the perimiter rule- half the width plus the height always =9, if you stop at n=120.

    I suppose if I’d been more curious at the time I might have delved deeper, but I was young and had other fish to fry. My chemistry instructors thought I should present it to the local ACS (which I did), but I think now maybe they just wanted not to be bothered and let me pester others.

    Isn’t it lucky, after all these decades, that I found you lot!

    Jess Tauber

       0 likes

Leave a Reply