基本介紹
- 中文名：ununoctium
- 類型：氣體元素
簡介,歷史,英文簡介,History,
簡介
第一百一十八號元素
核反應製取方程式:
Ununoctium的物理性質：
氣體，加壓可液化；
熔化點：≥-30℃；
沸點：≥-20℃；
歷史
Berkeley實驗室的V. Ninov等人於1999年發表了利用氪-86和鉛-208通過1n道生成118號元素的實驗結果[Nin99]，但結果於2001年宣布收回。2002年6月25日，Dubna的Yu. Ts. Oganessian在德國重離子研究中心GSI作的一次學術報告上報告了Dubna合成118號元素的新結果。入射束流48Ca的能量為5.1 MeV/u，對應複合核的激發能為29 MeV，束流強度為0.8 pmA靶為230 mg/cm2的純度為97.3%的249Cf（總重量為7.1 mg，自身每秒鐘放出2´109個a粒子）。總束流時間為75天，對應的總照射量為2´1019個束流粒子。實驗前估計，3n道的截面~0.5 pb，4n的截面<0.1 pb。整個實驗過程中觀察到兩個可能的事件。一個是2002年3月19日5:28得到的一個如下衰變鏈（選自Oganessian報告的照片），其中290116和286114均是第一次被觀察到。另一個是3月16日7:04觀察到的一個壽命為3.2 ms的自發裂變事件。
2006年10月16日，美國與俄羅斯科學家以鈣離子與鉲（Cf，Californium）碰撞製造UUo，並宣稱存在千分之一秒。但獲得確認尚需數年時間。
英文簡介
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.
