简介

历史

英文简介

History

简介

第一百一十八号元素

Uuo是一种人工合成的放射性化学元素，它的化学符号是Uuo，它的原子序数是118，属于惰性气体之一。

Ununoctium（1-1-8-ium），原子量为293，半衰期12毫秒。属于气体元素，化学性质很不活泼。

核反应制取方程式:

Ununoctium的物理性质：

气体，加压可液化；

熔化点：≥-30℃；

沸点：≥-20℃；

颜色：无色（和其他六种惰性气体（氦，氖，氩，氪，氙，氡）一样）。

历史

Berkeley实验室的V. Ninov等人于1999年发表了利用氪-86和铅-208通过1n道生成118号元素的实验结果[Nin99]，但结果于2001年宣布收回。2002年6月25日，Dubna的Yu. Ts. Oganessian在德国重离子研究中心GSI作的一次学术报告上报告了Dubna合成118号元素的新结果。入射束流48Ca的能量为5.1 MeV/u，对应复合核的激发能为29 MeV，束流强度为0.8 pmA靶为230 mg/cm2的纯度为97.3%的249Cf（总重量为7.1 mg，自身每秒钟放出2´109个a粒子）。总束流时间为75天，对应的总照射量为2´1019个束流粒子。实验前估计，3n道的截面~0.5 pb，4n的截面<0.1 pb。整个实验过程中观察到两个可能的事件。一个是2002年3月19日5:28得到的一个如下衰变链（选自Oganessian报告的照片），其中290116和286114均是第一次被观察到。另一个是3月16日7:04观察到的一个寿命为3.2 ms的自发裂变事件。

2006年10月16日，美国与俄罗斯科学家以钙离子与鉲（Cf，Californium）碰撞制造UUo，并宣称存在千分之一秒。但获得确认尚需数年时间。

英文简介

is the temporary IUPAC name for the superheavy element having atomic number of 118, currently the highest atomic number assigned to a reputedly discovered element (see elements discovered in the 21st Century). It has the temporary IUPAC element symbol Uuo.

Ununoctium probably shares similar properties of its group, the noble gases, resembling radon in its chemical properties, and so some researchers have referred to it as eka-radon. It is probably the second radioactive gaseous element and the first standard semiconductive gas.

Ignoring nuclear instability due to radioactivity, scientists expect that ununoctium is much more chemically reactive than xenon or radon. It would likely form stable oxides (UuoO3, etc.) as well as chlorides and fluorides.

History

The name ununoctium is used as a placeholder, as in scientific articles about the search for element 118. Transuranic elements (those beyond uranium) are, except for microscopic quantities, 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 systematic element name for more information). In 1999, researchers at Lawrence Berkeley National Laboratory announced the discovery of elements 116 and 118, in a paper published in Physical Review Letters. [2]

The researchers claimed to have performed the reaction:

The following year, they published a retraction after other researchers were unable to duplicate the results.[3] In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by principal author Victor Ninov.

The American group had intended to name it ghiorsium after Albert Ghiorso before having to retract their claim.

On October 10, 2006, researchers working at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, announced in Physical Review C that they had indirectly detected ununoctium-294 produced via collisions of californium-249 atoms and calcium-48 ions [4][5]:

The research team consisted of workers from JINR and the Lawrence Livermore National Laboratory in California, USA. The decay products of three atoms of ununoctium, not the atoms themselves, were observed in Dubna. A half-life of 0.89 ms was observed: 294Uuo decays into 290Uuh by alpha decay. 290Uuh is very unstable, decaying within a fraction of a second into 286Uuq, which may undergo spontaneous fission or undergo alpha decay into 282Uub, which will undergo spontaneous fission.