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Unbiquadium (pronounced /uːnbaɪˈkwɒdiəm/) is the temporary name of a hypothetical element in the periodic table that has the temporary symbol Ubq and atomic number 124.

In 2008, a team at GANIL, France, published results indicating that nuclei of unbiquadium had been produced at very high excitation energy, which underwent fission with measurable lifetimes. This important result suggests a strong stabilizing effect at Z=124 and points to the next proton shell at Z>120, not at Z=114 as previously thought.
Synthesis of unbiquadium nuclei

In a series of experiments, scientists at GANIL have attempted to measure the direct and delayed fission of compound nuclei of elements with Z=114, 120, and 124 in order to probe shell effects in this region and to pinpoint the next spherical proton shell. In 2006, with full results published in 2008, the team provided results from a reaction involving the bombardment of a natural germanium target with uranium ions:

\( \,^{238}_{92}\mathrm{U} + \,^{nat}_{32}\mathrm{Ge} \to \,^{308,310,311,312,314}\mathrm{Ubq} ^{*} \to \ \) fission.

The team reported that they had been able to identify compound nuclei fissioning with half-lives > 10−18 s. Although very short, the ability to measure such decays indicated a strong shell effect at Z=124. A similar phenomenon was found for Z=120 but not for Z=114.[1]


The name unbiquadium is an IUPAC systematic element name, the temporary name and symbol assigned to newly-synthesized and not-yet-synthesized chemical elements. A transuranic element receives a permanent name and symbol only after its synthesis has been confirmed. Transuranic elements (those beyond uranium) are, except for microscopic quantities and except for plutonium, always artificially produced, and usually end up being named for a scientist or the location of a laboratory that does work in atomic physics.

See also

* unbitrium−unbipentium

1. ^ http://hal.archives-ouvertes.fr/docs/00/12/91/31/PDF/WAPHE06_EPJ_preprint1.pdf

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