Comments on: Rebuilding the Periodic Table

By: David Bradley

David Bradley — Wed, 25 Feb 2009 09:15:25 +0000

By: David Bradley

David Bradley — Tue, 15 Jul 2008 10:30:53 +0000

My very good friend Martyn Poliakoff at Nottingham U has launched Periodic Videos - an online periodic table of the chemical elements with each element leading clickably to short, informative and often hilarious videos.

By: David Bradley

David Bradley — Thu, 22 May 2008 07:47:57 +0000

Doesn’t saying it is “a bit of both” imply that mathematics might be there if even if we aren’t? I.e. that it exists outside human awareness and was something we discovered rather than invented? What do you mean by there being infinitely many truths?

By: Melinda Green

Melinda Green — Thu, 22 May 2008 06:06:21 +0000

People have also argued intently about how many angels can dance on the head of a pin. Sometimes very smart people just make mistakes.

Invention or discovery? Mathematics is a bit of both. We invent mathematical systems that we think will be interesting, and then we explore them to discover interesting results that they give. The important point things to remember are

1) there’s not just one perfectly valid, perfectly complete and self-consistent mathematical system, and
2) within the interesting ones, there are infinitely many truths, nearly all of which are totally uninteresting.

In both cases we are deeply involved. We only spend time inventing and examining the interesting systems, and we only look to discover interesting truths in them and ignore everything else that is uninteresting *to us*.

By: David Bradley

David Bradley — Wed, 21 May 2008 07:33:10 +0000

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?

By: Melinda Green

Melinda Green — Wed, 21 May 2008 05:12:25 +0000

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.

By: Prof L J Sacks

Prof L J Sacks — Tue, 20 May 2008 07:22:30 +0000

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

By: David Bradley

David Bradley — Tue, 20 May 2008 06:56:27 +0000

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.

By: Melinda Green

Melinda Green — Tue, 20 May 2008 03:14:38 +0000

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.

By: eric scerri

eric scerri — Mon, 19 May 2008 20:33:40 +0000

Hi Melinda.

We may be talking at cross purposes. I am not discussing the best model for a particular purpose such as teaching this or that aspect of electronic configurations.

I am claiming that elements belong in particular groups and that the task of science is to discover the closest thing to the truth regarding the grouping of elements.

As I see it H and He belong in one particular group. It is not dependent on what properties one happens to focus on or at least it should not depend on this. If it does it means that the criteria that are being used are not good enough, not essential to the elements.

My suggestion for the essential criterion for ordering AND ALSO group membership is atomic number. The first is commonplace. The second is more radical and based on what I have written about atomic number triads in Journal of Chemical Education and the Jan-Feb issue of American Scientist. I would go as far as to say that atomic number triads are a better criterion for group membership that electronic configuration.

This is the case with Sc, Y, Lu and Lr for example as opposed to Sc, Y, La, Ac.

Published periodic tables seem to be divided. Atomic number triads argues for the first grouping and against the second one.

There is other physical evidence in favor of the first grouping.

Finally, can you send me a copy of your spiral representation at my UCLA chem department address please. See my website for detail.

regards,
eric scerri