Tuesday, January 12, 2016

The place of the periodic table

I can fully understand that Eric Scerri, who has done so much to explain, popularize and clarify the periodic table, would object to my suggestion in a Nature article that “chemists rarely need to refer to it” and that it “holds more interest and glamour for the public than it does for the working chemist”. These statements are too general; I should say “many” (most?) chemists. There are some who surely do use it, and a rather small group of others – Eric among them, of course – who expend a lot of time and thought on the right way to structure it. Those latter questions are interesting and valuable, and I regret that Eric seems to have been offended by an apparent implication (not intended) that they are not.

If I exaggerate, it’s to make a point, which is that it is not terribly good for chemistry if it is seen as being all about the periodic table – and that is the impression I think non-scientists often get. Not only does it obscure what most chemists do, but it leads to the idea that the quantum explanation of the periodic table means that chemistry is “just physics”, or that, now we know all the elements (except ones we make ourselves), “pure” chemistry is pretty much over as an academic discipline (if you don’t believe me, see here). And chemistry is not alone in the risks associated with giving too much emphasis to its organizational schemas, as I say. One could easily get the impression, from Higgs- and LHC-mania (which is fine in itself), that all physicists want to do is find new particles. Yet most physicists never need to consult the tabulation of the standard model, even mentally. Nor do most biologists need to know the genetic code (though of course they learn it anyway). This is not a question of whether these lists and tables and classifications are significant – of course they are. It is about guiding public perception away from the notion that this is what the respective disciplines are all about.

The periodic table is not a “mere list”. It is far richer than that. But chemistry as a whole is much, much richer still, because it is primarily about making things with, and not simply categorizing, its building blocks. I am not convinced that this is widely understood (Tom Lehrer’s song, for all that it’s fun, suggests as much), and I worry that at least some of the excitement about the new elements amounts to the perception that “hey, we’ve completed the list!” That’s the challenge that needs to be faced.


Eric Scerri said...

No offense taken Philip. I am glad you are raising these issues and happy to discuss further.

One point about the reductionism claim and the role of physics that you raise. The way I have come to think about this is that in a sense it's the other way round. Rather than emphasizing that quantum physics explains away the periodic table it's worth remembering that the periodic table helped to give birth to quantum mechanics. First J.J. Thomson used the periodic table in order to arrive at electronic configurations with his electron rings. Then Bohr set out to explain the periodic table with his more sophisticated electronic configurations that he claimed to have derived from his quantum theory. Then Pauli arrived at the Exclusion Principle by likewise trying to explain the periodic table.

I hope to respond more fully to your article sometime in the future. Another dimension to all this is the role of the periodic table in chemical education which I take it you would agree is utterly essential. Many professional chemists are also engaged in teaching of course. Your readers can see my website for books, articles and blogs on this and similar questions. Thanks for mentioning my work in this field. www.ericscerri.com

As you may have heard my proposal to form a IUPAC working group to look into the question of group 3 has been fully approved and you are of course in this group. Another indication perhaps that professional chemists do care about the periodic table. Why else waste time and resources on a "list"?


Eric Scerri
Department of Chemistry & BIochemistry

Eric Scerri said...

Hi again Philip,

Let me turn to your main point concerning whether or not working chemists refer to the periodic table.

As I see it the periodic table provides the major paradigm, in Kuhnian terms, for the whole of Inorganic if not quite all of chemistry.
Putting it another way the periodic table is the background framework. Perhaps not a theoretical framework since the periodic system is not a theory but nevertheless the framework and quite literally so.

Admittedly not every Inorganic chemistry uses the periodic table each and every day in the same way that they use their computer say but still the periodic system/table forms the backdrop against all research is being conducted.

We tend to take familiar things for granted and so it is with the periodic table. A chemist who denies it's importance could be compared to an impetuous teenager who is desperately rebelling against their family. They think they can ignore them but they actually depend on them.

On the question of reduction to physics now. Yes chemists appear to be the poor relation of physics in the popular imagination but as we both know they are not. More fundamental, which physics most surely is, does not mean better. This is another reason why the periodic table actually matters to chemists even if not as a practical tool for everyday reference. The periodic table is predominantly the domain of chemistry. It is a tool which chemists can appeal to, when necessary, without reaching for quantum mechanics. And a good deal of the time the periodic table gives a useful first approximation to a general chemical question as to how a particular element might behave.

So rather than implying that chemists don't draw much on the periodic table I think we should be encouraging chemists to treat the periodic system as one of the few things that is their own and that has not been usurped by the physicists. The periodic system is one chemistry's big ideas. The periodic table is just a concrete representation of that abstract relationship between the elements.

So perhaps this little debate comes down to the distinction between periodic table and periodic system. Surely you would want to uphold what I am saying about the importance of the periodic system, the background for chemistry even if not every chemists does not pick up an actual periodic table each and every day?

eric scerri

bschaeffer said...

The problem is that the standard table e.g. that of the IUPAC (International Union of Pure and Applied Chemistry) and almost others are not correct with quantum physics. I have even seen a book assumed to be quantum physics consistent but with the usual error. The correct presentation was from a french doctor of medicine, unknown in France, discovered by Eric Scerri in an american journal. I wrote some year ago to a french academician: he said that the periodic table doesn't need to be modified... Indeed, he knows only that the elements are integers from 1 to more than 100.

It seems to be not important that only 3 elements (H, La and Ac) are not at the right place but it contradicts quantum physics.

Bernard Schaeffer

Philip Ball said...

I’m glad there’s not really any disagreement here Eric. I think my impatience with public perceptions led me to a somewhat barren choice of words. It might be technically true that chemists aren’t constantly looking up the periodic table or discussing it in the coffee room, but only because it is of course so thoroughly assimilated a part of their mental landscape. What I wanted to get at here is the notion that many people seem to look at the periodic table and think “There it is: chemistry in a nutshell!” I worry too that some of the excellent book popularizing chemistry, such as Sam Kean’s The Disappearing Spoon and Hugh Aldersey Williams’ Periodic Tales, inadvertently reinforce this impression that chemistry is a tramp through the elements (even when that tramp is as engaging a tour as those guys provide). But I’m ambivalent even here, because like all chemists I feel a real kind of affection towards the elements, and so I understand the attraction.

But as I said, the wider concern is that this is just a part of the perception that science generally is a list of facts. I bet you have received those incredulous comments that you call yourself a scientist but don’t even know the gestation period of a rhinoceros or the distance to Betelgeuse. (I’m reminded of Einstein pointing out that he didn’t carry the speed of sound around in his head because he could always look it up.)

I do like your idea that the periodic table helped to guide quantum physics, rather than the latter “explaining” the former. And I’d have absolutely no quarrel with your assertion that the periodic table is central to chemical education. (It’s partly why my 10-year-old daughter has a mug with the table on it, though she’s now complaining that it’s out of date.)

I’d hate to think that my comments could have been interpreted as a denial of the importance of the periodic table. But I do think that, for plenty of chemists, it is important only in much the same sense that the standard model is important in physics: important in the sense that the bricks of a theatre are important for the performance taking place on stage. (Don’t think too hard about that analogy, but I hope you see what I mean about what then gets overlooked.) Whether chemists should be encouraged to think of it as “theirs” is less clear to me. I know what you’re driving at, but I can’t see that any part of the natural world belongs in any particular academic silo.

There was some debate on Twitter about nationalism in element-naming. I’d not want to give the impression that, now that France, Germany, Sweden, America, Russia, Poland and so on have “their” elements, Japan should be arbitrarily denied “theirs”. But I’m not particularly keen on any of it. I suppose one could argue that nationalistic names encode, in a way, a bit of history into the periodic table, but this all now seems part and parcel of the tiresome squabbling over priority of synthesis. Element-making is a noble and fascinating pursuit, but nationalistic naming threatens to convey an eternal absoluteness on priority judgements that are often somewhat subjective and grey. While accepting that everyone wants due recognition – we’re only human – I don’t like conventions that exacerbate the already corrosive culture of precedence in science. I’d rather not see flags stuck all over the moon and the asteroid belt, and I’m not keen on seeing it in the periodic table either. Well there you go: I must care rather deeply about it after all!