At Last, A Definitive Periodic Table?

  • DOI: 10.1002/chemv.201000107
  • Author: David Bradley
  • Published Date: 20 July 2011
  • Source / Publisher: ChemistryViews.org
  • Copyright: WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
thumbnail image: At Last, A Definitive Periodic Table?

Discussion Spawned Development in the Field

A recent Research Highlight on ChemistryViews.org on the nature of the Periodic Table of the Elements attracted a lot of readers and has stimulated an ongoing debate among those arguing as to whether or not there is a definitive format for this iconic tool. Intriguingly, however, the article and ensuing discussion has also spawned a development in this field courtesy of UCLA chemistry professor Eric Scerri.


"One of the most positive outcomes of the very popular 'Periodic Debate' discussion has been that the relative virtues of the so-called 'Stowe' and the 'left-step' periodic table, in various formats, have been vigorously discussed," Scerri says. "In the course of this debate I have come up with a compromise table which includes the best features of both types of systems."

Stowe Table

The Stowe table is named for Tim Stowe who published his system on a website several years ago but has, apparently, published nothing since. Chemists have attempted to track him down, but he seems to have vanished from the community without a trace, leaving behind an interesting periodic legacy. "Many people interested in the periodic table have tried to track him down," says Scerri, "but nobody has yet succeeded."


Stowe’s system is four dimensional in the following sense: the x and y axes depict values of the m and s quantum numbers. In the case of the s or spin quantum number values are either positive or negative, while the values of the m quantum number can range from -l, through 0 up to +l in integer steps. The z-axis is taken as the n or main quantum number representing the main shell. The fourth dimension, which obviously cannot be depicted spatially, is shown by the use of different colors each of which denotes a different value of the l quantum number. In this way, the Stowe table seeks to depict the four quantum numbers of the electron that differentiates each atom from the previous one in the sequence of increasing atomic numbers.


However, the Stowe representation has several drawbacks, which is where Scerri's new approach comes to the fore. The left-step table has received a great deal of attention in recent years. It was originally designed by the French engineer and polymath Charles Janet in the 1920s. However, with the advent of quantum mechanics and the quantum mechanical account of the periodic system it was realized that his system displays the elements in order of increasing n + l values of the differentiating electron. Many authors have claimed that this is a more natural system since electron filling accords with this criterion rather than increasing values of n.

New Modifications by Scerri

Scerri has now modified the left-step table by combining it with Stowe’s idea of using the quantum numbers explicitly to represent the elements in the periodic system. "The notion that n + l is more fundamental than n alone is key," says Scerri. "The format I have now constructed depicts the arrangement of the elements in this fashion for elements 1 to 65 inclusive and can be easily extended up to 118 the currently heaviest atom and indeed beyond to elements that will in all probability be
synthesized soon." In what he now calls the Stowe-Janet-Scerri periodic system each level represents a particular value of n + l which take the form of horizontal periods in the case of the original Janet table.


Following Scerri's introduction of this new layout in the comments of the ChemistryViews item, commenter Valery Tsimmerman, pointed out that Scerri's efforts in re-working the Stowe table is bringing us closer to the realization of the numerical and geometrical regularities of the Periodic System. Tsimmerman also claims to have devised the perfect Periodic Table based on the concept of tetrahedral sphere packing.

Tsimmerman's Concept of Tetrahedral Sphere Packing

Tsimmerman points out that chemists such as Henry Bent mentioned that every other alkaline earth atomic number equals to four times the pyramidal number, while Wolfgang Pauli noticed that length of periods are double square numbers: 2x(1, 4, 9, 16). This latter point is, Tsimmerman says, not surprising because square numbers are the sums of odd numbers 1, 1+3, 1+3+5, 1+3+5+7 ... We know the meaning of odd numbers in the periodic system. They are the lengths of s, p, d and f blocks. Adding the number of elements in block rows results in the lengths of the periods. Adding square numbers results in pyramidal numbers: 1, 1+4=5, 1+4+9=14, 1+4+9+16=30. Multiply them by four and you will get every other tetrahedral number 4, 20, 56, 120 ... Those are the atomic numbers of Be, Ca, Ba and Ubn. "Great scientists like Pauli, Niels Bohr and others were marveling at numerical relationships found in periodic system," says Tsimmerman. He suggests that Scerri's latest periodic table is not quite the final version and suggests that any further reworking of Stowe's table will take us closer to a definitive 3D table.


"I hope that this system will not be just another periodic table to add to the depository of tables that people dream up every so often but may represent a definitive step forward in the quest for improved periodic tables," Scerri told us.


  • Periodic Debate, David Bradley
    Mendeleev's Periodic Table is, for many, the symbol of chemistry but is the current layout the best one?
    including discussion mentioned in article

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5 Comments

Philip Stewart wrote:

Charts

I see that Stowe entitles his representation a 'chart'. I think that word was first used by John D Clark for his spirals; tell me if I'm wrong. I think it would be a good idea to use that as the general description of tables, spirals etc. as being less clumsy than 'representations'. I suppose it's a bit of a stretch to push it to 3-D versions, but perhaps we can just call those 'models'.

Thu Jul 28 08:51:16 UTC 2011

Eric Scerri wrote:

The search for Stowe closing in perhaps

As I mentioned to some of the people here via an E-mail it appears that the most definitive version of Stowe's table, along with a description of it appears in an I2R calendar for 1999. The company which issued these popular chemical calendars is still in existence and I intend to call them to see what I can discover about Stowe.

Thu Jul 28 02:02:49 UTC 2011

Valery Tsimmerman wrote:

On a side note

Some one sent me a picture from Science gallery in Dublin. Philip, Images of our periodic tables are displayed next to each other. I'll send you that picture, I'll copy Jess and Eric also.

Wed Jul 27 18:28:41 UTC 2011

Philip Stewart wrote:

Conflict

The two proposals are in fact Janet Version I a.k.a. Simmons 1947, and Stowe modified in the light of Janet Version III. I don't think the latter will ever be much used, if only because the sequence of values of Z has been lost. The conflict is essentially between Janet and Janet. Stowe resolves it by putting asterisks on the halogens and (ig)noble gases, so Eric could always pop an asterisk on H (I grant that hydrides are more like halides than acids are like salts). I still vote for Valery's transformation of Janet III, but it all goes back to Janet.

Wed Jul 27 17:42:27 UTC 2011

Valery Tsimmerman wrote:

One more quick note on He/Be

Many elements in periodic system have structural similarities, but some are stronger than others. To determine the strongest structural similarities we should look at the characteristics of outer electrons. Them most definitive of structural characteristics is electron orbital angular momentum. ______Angular momentum of both outer electrons of He and Be and other alkaline earths is zero with quantum number l=0. Angular momentum of outer electrons of Ne, Ar, Kr and other "not so inert" gases is not (l=1).

Wed Jul 27 15:31:18 UTC 2011

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