.....15.9994?! Where ARE you?

For a good time pondering the slow, reformative pace of scientific fine tuning, click over to the Los Angeles Times where Thomas H. Maugh II wrote up in good style some  small, obscure, amusing, astounding news. The atomic weights of ten elements including some that everybody knows about have been wrong. (No dysprosium or its ilk on this list, even though the NYTimes‘s Keith Bradsher, in story one must call a must-read even though it’s not strictly science, just wrote balefully of a feared dysprosium shortage).

Sorry for the digression in parentheses there. Anyway, the Periodic Table had it either wrong or sort of wrong, depending where one is, and that has nothing to do with relativity theory.  This is big news of the most arcane sort. If Jonah Lehrer, who wrote that big New Yorker story (previous post) on the dodginess of nearly all published scientific results, had known about this he’d probably blame it on the Decline Effect. But it is not that – it’s just that the hard and fast atomic weights of some elements are not, out there in nature, constant. That’s because the periodic table doesn’t list all isotopes separately, but gives each element an aggregate atomic weight representing the average of its naturally occurring isotopes adjusted for their relative abundance.

Maugh calls it, in his lede, the Extreme Makeover, Chemistry Edition. The elements affected in a revision, proposed by researchers from the US Geological Survey and University of Calgary, are hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine, and thallium. Rather than having single atomic weights, each will now get a small range to reflect that in various geologic settings the relative abundances of the isotopes may be different, changing the average an oonch.

It’s not often a science writer has to, or gets to depending on one’s point of view, explain what an atomic weight is and what an isotope is. Or where the big news is in the change of a number attached to oxygen from its now-canonical 15.9994 to the range 15.999 03 to 15.999 77.

A few other outlets ran with it – not many considering two press releases gave the news a boost.

Other stories:

• Canadian Press – Scott Edmonds: Atomic weight of 11 elements on what was a constant periodic table are changing. Hmmm. The LATimes said ten elements. The difference is that an additional element, germanium, has also been revised slightly, but apparently not because of isotope abundance fuzziness. He tells what he calls a really bad chemistry joke, and that’s about right for this riddle. What element of the periodic table obeys all laws? A: Copper. As in cop, get it. Copper’s At.Wt. stays the same. This story also carries the news that an additional set of multi-isotope elements are under scrutiny and may eventually be in for a change recommendation as well.
• Ottawa Citizen/Postmedia News – Sarah McGinnis: It ain’t heavy, it’s hydrogen: Scientists updating periodic table ;
• CNET – Jennifer Guevin: Periodic table gets weighty update ; The story, plus a sarcastic aside. He refers to the “snappily named” International Union of Pure and Applied Chemistry’s Commission on Isotopic Abundances and Atomic Weights. I’m pretty good at acronyms, but never would I nor anybody else be able to tell you, unless they belong to the thing, the meaning of IUPACCIAAW.

*UPDATE: More stories:

• Scientific American – David Harris: Mass Migration: Chemists Revise Atomic Weights of 10 elements ; Good basic chemistry explainer except ….. Edmonds’s story from CP, a few bullets up, says these ten are merely the first ones for which the group has calculated a range, and an additional series is in the works. Harris says these ten are it – everything else has just one stable isotope. Hmm. Iron, for one, has four stable isotopes and it’s not on the list. Tin has ten.
• *UPDATE to UPDATE – Harris, not long after this post went up, did amend his piece with a simple re-wording, evading the error on the diversity of elements with multiple stable isotopes. He and I had just sat on the same panel at the AGU meeting in SF – he moderated splendidly a rehash of the arsenic microbe story – and he’d told me in the press room later he too had done this periodic table story. Gad – felt bad chiding him even slightly on it.

Grist for the Mill:

University Calgary Press Release with links to the two journal articles; USGS Press Release ;

- Charlie Petit

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