Apr 18, 2008
Rebuilding the Periodic Table
I’m bored with looking at the standard periodic table on my office wall. It has been useful over the years, of course, and has been exploited and sexploited too in the form of a periodic table of yoga and a sexy PT. It has also been hacked apart, cut and paste into different formats, created as illiminated wall cases, woodworked into furniture, spiralled, spherized, and generally rebuilt in almost every imaginable way ever since Mendeleev first dreamed of laying out his elemental cards according to the periodicity of elemental properties.
Now, in an effort to inspire chemists to reconsider the foundations of the periodic table, chemical philosopher, best-selling science author and my good friend, Eric Scerri of the University of California, Los Angeles, is building a new way to classify the chemical elements one step at a time.
Writing in the latest issue of the Journal of Chemical Education (PDF 2008, 85, 585-589), Scerri explains how the periodic table initially arose from the discovery of atomic weight triads but he now suggests that chemists should
recognize
the fundamental
importance of atomic
number triadschemists should recognize the fundamental importance of atomic number triads.
This sea change in elemental attitude would enhance the periodic table by classifying the elements at a fundamental level as basic substances. As such, he and his colleagues have developed a new version of the “left-step” periodic table, which looks very different from the conventional PT. In the new layout, with its step-like pattern actinides and lanthanides are no longer relegated to a standalone box, but form the first step of the PT.
Climbing right to the transition metals (Fe, Mn, Ir, Sg et al) on the next step and then to the non- and semi-metals, such as boron carbon, oxygen, silicon etc and finally a step in which the halogens (fluorine, chlorine…), noble gases (neon, xenon…), alkali metals (potassium, sodium…) and alkaline earth metals (beryllium, calcium…) form the final highest step on the right. Hydrogen tops the halogen column and helium crowns the noble gases rather than acting as the outer beacons as with the conventional layout. (Click the graphic for a clearer, full-size view).
“The left step table has been around for sometime,” Scerri told me, “but I am modifying it to accommodate two atomic number triads which would otherwise be absent. They are He, Ne, Ar which ceases to exist as a triad in the usually encountered left-step table and H, F, Cl which does not exist either in the conventional medium-long form table or the usually encountered left-step table.”
In the grander scheme of things, whatever form the Periodic Table takes in the future matters not to those of us who sing, so we end with a song, the periodic table song from Tom Lehrer (who was 80 on April 9, 2008 and gets a mention in the Official Google Blog this week), known simply as The Elements.
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I agree, yes, the universe cannot “know” anything in the sense that we do, and yes mathematics seems like a human invention used to organise the patterns we see. However, aren’t there those who have argued that we didn’t invent mathematics, we discovered it?
db
David, you say that atomic number is somehow a special quality of atoms beyond what is useful to beings like ourselves. That it’s intrinsically special to the universe itself. It’s just not so. Your reasoning is that this property is mathematically simple, and that makes it special. But what’s so special about our mathematics other than the fact that it’s useful to us? Nature doesn’t really prefer forms because of their ability to be described by elegant mathematics. It’s more that we tend to study those physical and mathematical systems that we find to be elegant and useful for our needs. It should therefore be no surprise that those physical and mathematical systems complement each other nicely because what they really have in common is us. You even hinted at the key truth with your last line in which you said that if not even mathematics is intrinsic to the universe, then everything is subjective. Now *that* is the real truth.
Maybe I should try to demystify that last statement a little by replacing the word “everything” with “every thing”. “Everything” mostly means the universe itself which I believe is not subjective. I.E. it will continue to exist whether or not any living things are here to perceive it. “Every thing”, on the other hand, refers to all “things”, and things are things only within minds that decide so. We might agree that there are two clouds in the sky but that’s just an agreement that we happen to hold. The universe only knows that there are regions of greater or lesser amounts of matter. The universe knows of no such things as clouds or people or even atoms.
Agreeing with Eric concerning the need to place H and He in an appropriate family, I submit that for both the element and its compounds (orlack thereof), H belongs with the (other) Halogens and He with the other Noble Gases.
The problem for many is that we (incorrectly, in my view) refer to the number of valence electrons in assigning these elements to the Alkali and Alkaline Earth families, despite the recognized uniqueness of the First Row. A better question is “how many electron does it take to fill the valence shell?”; then they automatically fall into the “right” families. In a previous submission to Sciencebase Science Blog I described briefly why H is better considered as hydride ion in ALL compounds, from acids to methane to salt-like hydrides of the first two families. That this provides both qualitative and quantitative predictive ability for a wide range of compounds – including many that must currently be treated as “special” cases – argues for further consideration of this postulate.
Larry Sacks
Melinda, Eric that was the point to which I was alluding, that any “pattern” requires an observer. However, I think Eric is right in that there is presumably some essence, the essential or elemental part of atoms that lies outside our subjectivity. One has to assume that, regardless of the symbols used, 2 follows 1 and 1+1 = 2. Mathematics seems to be intrinsic to the universe regardless of our position as observers, if it isn’t, then everything is subjective.
db
Neither the periodicity nor any classification is intrinsic to nature. Periods of what? Where do these classes come from? They come from us to suit our particular purposes. The only property intrinsic to the elements is atomic number, and that only by our definition of the term “element”. We study the electronic families that different elements fall into because doing so tends to yield results that are interesting *to us*. Other intelligent beings could just as validly decide that the most important classification is by size, or density, or even smell for that matter! I don’t believe that there are any ways to describe anything about the universe without a relative position from which to describe. Every description requires a describer. Subjectivity is not just an annoyance, it is the source of all meaning.