Ununoctium is the temporary IUPAC name[9] for the transactinide element having the atomic number 118 and temporary element symbol Uuo. It is also known as eka-radon or element 118, and on the periodic table of the elements it is a p-block element and the last one of the 7th period. Ununoctium is currently the only synthetic member of Group 18. It has the highest atomic number and highest atomic mass of all discovered elements.
The radioactive ununoctium atom is very unstable, and since 2002, only three atoms (possibly four) of the isotope 294Uuo have been detected.[10] While this allowed for very little experimental characterization of its properties and possible compounds, theoretical calculations have resulted in many predictions, including some unexpected ones. For example, although ununoctium is a member of Group 18, it may possibly not be a noble gas, unlike all the other Group 18 elements.[1] It was formerly thought to be a gas but is now predicted to be a solid under normal conditions due to relativistic effects.[1]
In 1999, researchers at Lawrence Berkeley National Laboratory made use of these predictions and announced the discovery of ununhexium and ununoctium, in a paper published in Physical Review Letters,[12] and very soon after the results were reported in Science.[13] The researchers claimed to have performed the reaction
In 2011, the IUPAC has evaluated the 2006 results of the Dubna-Livermore collaboration and concluded that they did not meet the criteria for discovery.[23]
Because of the very small fusion reaction probability (the fusion cross section is ~0.3–0.6 pb = (3–6)×10−41 m2) the experiment took 4 months and involved a beam dose of 4×1019 calcium ions that had to be shot at the californium target to produce the first recorded event believed to be the synthesis of ununoctium.[6] Nevertheless, researchers are highly confident that the results are not a false positive, since the chance that the detections were random events was estimated to be less than one part in 100,000.[24]
In the experiments, the alpha-decay of three atoms of ununoctium was observed. A fourth decay by direct spontaneous fission was also proposed. A half-life of 0.89 ms was calculated: 294Uuo decays into 290Uuh by alpha decay. Since there were only three nuclei, the half-life derived from observed lifetimes has a large uncertainty: 0.89+1.07
−0.31 ms.[7]
In a quantum-tunneling model, the alpha decay half-life of 294Uuo was predicted to be 0.66+0.23
−0.18 ms[25] with the experimental Q-value published in 2004.[26] Calculation with theoretical Q-values from the macroscopic-microscopic model of Muntian–Hofman–Patyk–Sobiczewski gives somewhat low but comparable results.[27]
Following the success in obtaining ununoctium, the discoverers have started similar experiments in the hope of creating unbinilium from 58Fe and 244Pu.[28] Isotopes of unbinilium are predicted to have alpha decay half lives of the order of micro-seconds.[29][30]
Hey friends Einstein had suggested that if we purify uranium-235 worlds best atomic bomb would be created but i suggest that if un-unoctium is purified worlds best atomic bomb would be created but it being a synthetic element the chances are too low
Source::http://en.wikipedia.org/wiki/Ununoctium
The radioactive ununoctium atom is very unstable, and since 2002, only three atoms (possibly four) of the isotope 294Uuo have been detected.[10] While this allowed for very little experimental characterization of its properties and possible compounds, theoretical calculations have resulted in many predictions, including some unexpected ones. For example, although ununoctium is a member of Group 18, it may possibly not be a noble gas, unlike all the other Group 18 elements.[1] It was formerly thought to be a gas but is now predicted to be a solid under normal conditions due to relativistic effects.[1]
Unsuccessful attempts
In late 1998, Polish physicist Robert Smolańczuk published calculations on the fusion of atomic nuclei towards the synthesis of superheavy atoms, including ununoctium.[11] His calculations suggested that it might be possible to make ununoctium by fusing lead with krypton under carefully controlled conditions.[11]In 1999, researchers at Lawrence Berkeley National Laboratory made use of these predictions and announced the discovery of ununhexium and ununoctium, in a paper published in Physical Review Letters,[12] and very soon after the results were reported in Science.[13] The researchers claimed to have performed the reaction
- 86 36Kr + 208 82Pb → 293 118Uuo + n.
Discovery claims
The first decay of atoms of ununoctium was observed at the Joint Institute for Nuclear Research (JINR) by Yuri Oganessian and his group in Dubna, Russia, in 2002.[16] On October 9, 2006, researchers from JINR and Lawrence Livermore National Laboratory of California, USA, working at the JINR in Dubna, announced[7] that they had indirectly detected a total of three (possibly four) nuclei of ununoctium-294 (one or two in 2002[17] and two more in 2005) produced via collisions of californium-249 atoms and calcium-48 ions:[18][19][20][21][22]In 2011, the IUPAC has evaluated the 2006 results of the Dubna-Livermore collaboration and concluded that they did not meet the criteria for discovery.[23]
Because of the very small fusion reaction probability (the fusion cross section is ~0.3–0.6 pb = (3–6)×10−41 m2) the experiment took 4 months and involved a beam dose of 4×1019 calcium ions that had to be shot at the californium target to produce the first recorded event believed to be the synthesis of ununoctium.[6] Nevertheless, researchers are highly confident that the results are not a false positive, since the chance that the detections were random events was estimated to be less than one part in 100,000.[24]
In the experiments, the alpha-decay of three atoms of ununoctium was observed. A fourth decay by direct spontaneous fission was also proposed. A half-life of 0.89 ms was calculated: 294Uuo decays into 290Uuh by alpha decay. Since there were only three nuclei, the half-life derived from observed lifetimes has a large uncertainty: 0.89+1.07
−0.31 ms.[7]
- 294 118Uuo → 290 116Uuh + 4He
- 245 96Cm + 48 20Ca → 290 116Uuh + 3 n,
In a quantum-tunneling model, the alpha decay half-life of 294Uuo was predicted to be 0.66+0.23
−0.18 ms[25] with the experimental Q-value published in 2004.[26] Calculation with theoretical Q-values from the macroscopic-microscopic model of Muntian–Hofman–Patyk–Sobiczewski gives somewhat low but comparable results.[27]
Following the success in obtaining ununoctium, the discoverers have started similar experiments in the hope of creating unbinilium from 58Fe and 244Pu.[28] Isotopes of unbinilium are predicted to have alpha decay half lives of the order of micro-seconds.[29][30]
Hey friends Einstein had suggested that if we purify uranium-235 worlds best atomic bomb would be created but i suggest that if un-unoctium is purified worlds best atomic bomb would be created but it being a synthetic element the chances are too low
Source::http://en.wikipedia.org/wiki/Ununoctium
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