Unusual sub-atomic particle distributions calculated for oganesson

  • Feb 20, 2018

A team of physicists including nuclear theorists Witold Nazarewicz and Bastian Schuetrumpf of the NSCL and FRIB at MSU has calculated the distributions of sub-atomic particles in an atom of oganesson (super-heavy element 118) and found them to be highly unusual, both within the nucleus and in the electron cloud surrounding it. Other members of the research team include Massey University (New Zealand) physicists Peter Schwerdtfeger and Paul Jerabek.

The very large number of protons, neutrons, and electrons in oganesson causes their behavior to depend more on relativistic effects than is observed in lighter elements (though elements as light as gold and mercury do show some subtle effects of relativistic behavior). The shell structure seen in the electron clouds of lighter elements, which gives rise to their chemical behavior, is significantly washed out in the electron cloud of an oganesson atom, nearly to the point of considering it a smooth distribution rather than a set of shells with low-density gaps between them. There is a similar decrease in shell-like structure for the protons and neutrons within the nucleus of an oganesson atom relative to that seen in the nuclei of lighter atoms.

The structure and chemical behavior of oganesson has to be studied using computational modelling, as it is one of the heaviest elements to have been synthesized to date. Fewer than ten oganesson atoms have been confirmed as having been produced so far, and the oganesson isotopes involved have half-lives of well under a second, leaving no time for using chemical methods to observe their electron distributions. On the periodic table, oganesson is the heaviest member of group 18, the "noble gases". There have been theoretical suggestions that, unlike the other members of the group, oganesson might be solid at room temperature rather than a gas, and the results in this recent paper support this idea, though the practical consequences of this property are limited, given the incredible scarcity of oganesson atoms.

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