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Atomic Weight Not So Constant

Posted by kdawson on from the thulium-and-thalium dept.

DangerousBeauty writes "Yahoo has a Canadian Press story up about new changes to the periodic table of elements concerning the weights of specific elements — it seems that the weights fluctuate based on where they are found in nature. Quoting: '"People are probably comfortable with having a single value for the atomic weight, but that is not the reality for our natural world," says University of Calgary associate professor Michael Wieser.' He is is secretary of the International Union of Pure and Applied Chemistry's Commission on Isotopic Abundances and Weights."

5 of 147 comments (clear)

  1. Actual Link to Document by Fluffeh · · Score: 5, Informative

    Link to actual article is:
    link

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    1. Re:Actual Link to Document by chichilalescu · · Score: 5, Informative

      Yes. thank you for that link. Anybody with minimal knowledge of how atomic weights are computed (i.e. a weighted average of the atomic masses of the various isotopes) can guess that if the concentrations of isotopes are different in different samples, the "atomic weight" will be different.
      I went and read the famous abstract anyway. quote: "This fundamental change in the presentation of the atomic weights represents an important advance in our knowledge of the natural world and underscores the significance and contributions of chemistry to the well-being of humankind in the International Year of Chemistry 2011."
      This article is just about the results of some measurements. ok, useful measurements, but NOT an important advance in our knowledge of the natural world.

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    2. Re:Actual Link to Document by Interoperable · · Score: 5, Informative

      Thanks. The article makes it clear that the major change here is that the way in which atomic weights will be presented is changing. It's not just that they're being updated to reflect a more complete measurement, it's that atomic weights will now be represented as a range of possible values rather than a single value. It's not every day that the way in which information is presented in the periodic table changes.

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      So if this is the future...where's my jet pack?
  2. Re:I don't get it by Sockatume · · Score: 5, Informative

    They're recalculating the average atomic weight, the one on the periodic table, based on the abundances of the different isotopes in nature. If you're trying to calculate the mass of, say, 300,000 molecules of something, you use the average atomic weight and don't try to figure out what isotope each atom is.

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    No kidding!!! What do you say at this point?
  3. Comment removed by account_deleted · · Score: 5, Informative

    Comment removed based on user account deletion