Wednesday, 14 April 2010

New element!

A paper, just published in Physical Review Letters, has announced the first observation of element 117. This element, which will only be named when confirmed by an independent experiment and ratified by IUPAC, has been observed in an collaborative experiment between groups in Russia and the USA. The experiment took an isotope of Calcium and an isotope of an already rather heavy synthetic nucleus Berkelium, and produced two different isotopes of element 117. These isotopes decayed by a combination of alpha decay and fission, with a chain of decays that left a trail from which element 117 could be deduced. The observation gives further evidence that there may be more long-lived elements in the region.

There is no element 117 on Earth, but it is possible that it is produced in supernovae. Better understanding of the superheavy elements created in the lab helps us understand element formation in the stars, as well as the way in which protons and neutrons interact to give stable nuclei.


  1. The isotope with mass number A=294 (so 117 protons, 177 neutrons) had a mean lifetime of 112 ms (i.e. around a tenth of a second). The isotope with A=293 had a lifetime of 21ms.

    Not terribly long, but then Beryllium-8, a much lighter nucleus, vital for the formation of carbon in stars, only lives for 0.000000000000006ms!

  2. how long does it have to live to be considered an element?

  3. That's quite a tricky question, really. Beryllium-8 isn't usually considered as a real nucleus, just a short lived resonant state of two Helium-4 nuclei. Basically it has to live long enough to undergo some process that is characteristic of the particular isotope, like rotating once or undergoing some other internal excitation.

  4. Usually it should be stable enough for single-atom chemical analysis. Currently in Russia there are such experiments, which will try to figure out what are the chemical properties of 113 and 115 elements.
    Today we know that actinides are the heaviest group of elements after the rare-Earth elements. The chemistry of the new superheavy elements suggests that we are wrong. There is a new group of elements in the periodic table. 117 has to be one of them. It is amazing that in this area of research chemistry and nuclear physics work together again. Both in the experiments and in the theory.

  5. It'll be pretty exciting to work out the chemistry of these elements, especially if it turns out that there will be a new group and that 118 won't be a noble gas. I'd have thought that atomic Hartree-Fock calculations would be reliable enough to tell whether there would be a new group or not, but I don't really know enough of the details to be sure. I certainly find it amazing that they can do chemistry on single atoms. Fantastic stuff.