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Isotopes of ununseptium

Ununseptium (Uus) is the latest element to have been synthesized; much of the data are theoretical. It has no stable isotopes. A standard atomic mass cannot be given.


Z(p) N(n)  
isotopic mass (u)
half-life nuclear
(mole fraction)
range of natural
(mole fraction)
excitation energy
291Uus 117 174 291.20656(95)# 0.97 ns
292Uus 117 175 292.20755(101)# 1 ns
293Uus 117 176 14 (+11, -4) ms[1]
294Uus 117 177 78 (+370, -36) ms[1]


* Values marked # are not purely derived from experimental data, but at least partly from systematic trends.
* Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values from Ame2003 denote one standard deviation. Values from IUPAC are expanded uncertainties.


1. ^ a b Yu. Ts. Oganessian et al., Synthesis of a New Element with Atomic Number Z=117, Phys. Rev. Lett. 104, 142502 (2010). DOI: 10.1103/PhysRevLett.104.142502.

External sources

* Isotope masses from Ame2003 Atomic Mass Evaluation: G. Audi, O. Bersillon, J. Blachot, A.H. Wapstra, The Nubase evaluation of nuclear and decay properties, Nucl. Phys. A729 (2003) 3-128.
* Isotopic compositions and standard atomic masses from Atomic Weights of the Elements: Review 2000 (IUPAC Technical Report). Pure Appl. Chem., Vol. 75, No. 6, pp. 683–800, (2003).

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