At Last, A Definitive Periodic Table?

  • DOI: 10.1002/chemv.201000107
  • Author: David Bradley
  • Published Date: 20 July 2011
  • Source / Publisher:
  • 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 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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Philip Stewart wrote:

HeBe, Goddess of Youth!

Chemistry is mainly limited to the behaviour of substances over a narrow rang of temperatures and pressures on a watery planet. Physics is far more general and has given us information that can be used to explain the properties that chemists are interested in, but surely it is that more general view that should take priority. Anyway, I don't understand how Eric can be so stuck on the properties of He and at the same time be so enthusiastic about the Stowe table, which is very much a physicist's representation, with H and He under Li and Be.

Fri Jul 22 21:15:07 UTC 2011

Valery Tsimmerman wrote:

A Definitive Periodic Table?

If Periodic Table layout had already been decided by the chemists and the physicists are in agreement with them, why do we even wasting our time discussing it? The Last, Definitive Periodic Table has been around since beginning of 1900's. No point to discuss it further. Right?____ By the way, having full shells do not quite make He structurally similar to Ne. Those shells happen to be different and He, just like Be, do not have p-electrons which are abundant in Ne .____ Also, physicists do use Left Step PT and that is why it is called Spectroscopic Table.___ Talking about use of the Periodic Table, I have not heard that anybody has been using any other layouts, besides Mendeleev's short form in some East European countries and very, very few people use ADOMAH Periodic Table to teach about electron configurations as well as to prepare home work. That is about it for now.

Fri Jul 22 20:50:16 UTC 2011

Eric Scerri wrote:

What to do with helium

Valery, "structurally" He is as much like Ne (full shell) as it is like Be. Why should number of electrons present take presence over number if electrons absent for a full shell? If what you say about atoms being more relevant than properties were correct then physicists would have accepted the left-step table long ago. They have not because they are too sensible to believe that chemistry is nothing but present day quantum physics. They give the last word on the periodic table to chemists and chemists will not place He in the alkaline earths for the time being at least. Of course we can indulge in science fiction and suppose that in 300 years time there will be chemical evidence for placing He above Be but is that really what this is about? eric eric

Fri Jul 22 20:05:38 UTC 2011

Valery Tsimmerman wrote:

Ist memeber rule

I am okay with leaving first member "rule" as an observation for awhile. But it is hard to deny that structurally He is closer to Be than to Ne. The question is rather what Periodic system is supposed to classify. Is this classification of atoms or it is classification of their behavior? If it is classification of atoms, then He should be next to Be, as well as H next to Li. If this is classification of behavior, then Eric is right.____Reading Mendeleev's words "...Properties, such as the optical and even the electrical or magnetic ones, cannot serve as basis for the system naturally, since one and the same body, according to the state in which it happens to be at the moment, may show enormous differences in this regard..." makes me believe that he would be in support of classification based on attributes of atoms, not on properties, had he known what we now know____ In that case there would be only one periodic table. Isn't it what you are looking for?

Fri Jul 22 16:08:38 UTC 2011

Philip Stewart wrote:

First members

Until the first-member 'rule' can be deduced from first principles it will remain an observation rather than a rule, but H and He are the elements for which oddness can be so deduced; it follows from the peculiarity of the K shell, which allows only one orbital, also the fact that removal of electrons leaves a naked proton..

Fri Jul 22 13:50:11 UTC 2011

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