Ununoctium

Ununoctium: the essentials

 Brief description: experiments conducted at Dubna in Russia at the Flerov Laboratory of Nuclear Reactions (by workers from the Joint Institute for Nuclear Research in Russia and the Lawrence Livermore National Laboratory in the USA) indicate that element 118 (ununoctium, Uuo) was produced. Not too much though, one atom in the spring of 2002 and two more in 2005.

Table: basic information about and classifications of ununoctium.

Name: Ununoctium Symbol: Uuo Atomic number: 118 Atomic weight: [ 294 ] Standard state: presumably a gas at 298 K CAS Registry ID: 54144-19-3

Group in periodic table: 18 Group name: Noble gas Period in periodic table: 7 Block in periodic table: p-block Colour: unknown, but probably a colourless gas Classification: Non-metallic

Isolation

Isolation: experiments conducted at Dubna in Russia at the Flerov Laboratory of Nuclear Reactions (by workers from the Joint Institute for Nuclear Research in Russia and the Lawrence Livermore National Laboratory in the USA) indicate that element 118 (ununoctium, Uuo) was produced. Not too much though, one atom in the spring of 2002 and two more in 2005.

The 2002 experiment involved firing a beam of ⁴⁸₂₀Ca at ²⁴⁹₉₈Cf. The experiment took 4 months and involved a beam of 2.5 x 10¹⁹ calcium ions to produce the single event believed to be the synthesis of element 118 (ununoctium) as the ²⁹⁴₁₁₈Uuo isotope. Three neutrons are released during this process

²⁴⁹₉₈Cf + ⁴⁸₂₀Ca → ²⁹⁴₁₁₈Uuo + 3¹n

This ununoctium isotope then loses three alpha particles in rapid succesion:

²⁹⁴₁₁₈Uuo → ²⁹⁰₁₁₆Uuh + ⁴₂He (1.29 milliseconds)

²⁹⁰₁₁₆Uuh → ²⁸⁶₁₁₄Uuq + ⁴₂He (14.4 milliseconds)

²⁸⁶₁₁₄Uuq → ²⁸²₁₁₂Uub + ⁴₂He (230 milliseconds)

The ²⁸²₁₁₂Uub species then undergoes spontaneous fission (denoted SF) to other species. An important part of this work was additional work synthesising isotopes of element 116 through irradiation of ²⁴⁵Cm (as opposed to ²⁴⁹Cm referred to above).

²⁴⁵₉₈Cf + ⁴⁸₂₀Ca → ²⁹⁰₁₁₆Uuh + 3¹n

Analysis of this reaction very clearly indicates that ²⁹⁰₁₁₆Uuh is indeed a decomposition product of ²⁹⁴₁₁₈Uuo. This research was reported at an IUPAC conference in China (Yu. Ts. Oganessian, "Synthesis and decay properties of superheavy elements", Pure Appl. Chem., 2006, 78, 889-904.) in August 2006 and then more recently in Phys Rev C [Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, R. N. Sagaidak, I. V. Shirokovsky, Yu. S. Tsyganov, A. A. Voinov, G. G. Gulbekian, S. L. Bogomolov, B. N. Gikal, A. N. Mezentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, K. Subotic, V. I. Zagrebaev, G. K. Vostokin, M. G. Itkis, K. J. Moody, J. B. Patin, D. A. Shaughnessy, M. A. Stoyer, N. J. Stoyer, P. A. Wilk, J. M. Kenneally, J. H. Landrum, J. F. Wild, and R. W. Lougheed, "Synthesis of the isotopes of elements 118 and 116 in the ²⁴⁹Cf and ²⁴⁵Cm+⁴⁸Ca fusion reactions", Phys. Rev. C, 2006, 74, 044602].

Earlier, a team of Berkeley Lab scientists announced in 1999 the observation of what appeared to be element 118 but retracted the claim after several confirmation experiments failed to reproduce the results. This means that the following apparently is wrong. Please see this page for more details. In this work it was claimed that elements 118 and 116 were formed by accelerating a beam of krypton-86 (⁸⁶₃₆Kr) ions to an energy of 449 million electron volts and directing the beam onto targets of lead-208 (²⁰⁸₈₂Pb). After 11 days work, just three atoms of the new element were identified. The production rates for element 118 are approximately one in every 10¹² interactions.

²⁰⁸₈₂Pb + ⁸⁶₃₆Kr → ²⁹³₁₁₈Uuo + ¹n

The element 118 nucleus was said to decay less than a millisecond after its formation by emitting an α-particle resulting in an isotope of element 116 (mass number 289, containing 116 protons and 173 neutrons). This isotope of element 116 undergoes further α-decay processes to an isotope of element 114 and so on down to at least element 106 (seaborgium).

²⁹³₁₁₈Uuo → ²⁸⁹₁₁₆Uuh + ⁴₂He (0.12 milliseconds)

²⁸⁹₁₁₆Uuh → ²⁸⁵₁₁₄Uuq + ⁴₂He (0.60 milliseconds)

²⁸⁵₁₁₄Uuq → ²⁸¹₁₁₂Uub + ⁴₂He (0.58 milliseconds)

²⁸¹₁₁₂Uub → ²⁷⁷Ds + ⁴₂He (0.89 milliseconds)

²⁷⁷Ds → ²⁷³₁₀₈Hs + ⁴₂He (3 milliseconds)

²⁷³₁₀₈Hs → ²⁶⁹₁₀₆Sg + ⁴₂He (1200 milliseconds)

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Ununoctium	Ununoctium
Ununoctium	Ununoctium
Ununoctio	Ununoctio
Ununoctium	Ununoctio