Bohrium 化学特性,用途語,生産方法
解説
ボーリウム，Bh．原子番号107の元素．電子配置[Rn]5f 146d57s2の周期表7族元素．周期表でレニウムの下に位置する(エカレニウム)．1976年，ソビエト(当時)のドゥブナ原子核合同研究所(JINR)で，209Bi を標的として310 cmサイクロトロンで加速した 54Cr で衝撃して，質量数261の核種を得たと報告した．1981年，ドイツの重イオン研究所GSIは，同じ方法で質量数262の核種を合成，1983年にJINRもこれを確認した．質量数260～275の同位体核種が知られている．267Bh がもっとも長寿命で半減期17 s(α崩壊)．273,274Bh は半減期90 min と推定されている．GSIグループは元素名としてN.H.D. Bohr(ボーア)の名前からニールスボーリウム Nsを提案したが，IUPACは姓のみを選択し，ボーリウムを採択した(1997年)．室温で固体の銀白色または灰色の金属とされる．
物理的性質
Unnilseptium, or bohrium, is artificially produced one atom at a time in particle accelerators.In 1976 Russian scientists at the nuclear research laboratories at Dubna synthesizedelement 107, which was named unnilseptium by IUPAC. Only a few atoms of element 107were produced by what is called the “cold fusion” process wherein atoms of one element areslammed into atoms of a different element and their masses combine to form atoms of a newheavier element. Researchers did this by bombarding bismuth-204 with heavy ions of chromium-54 in a cyclotron. The reaction follows: Bi-209 + Cr-54 + neutrons = (fuse to form)Uns-262 + an alpha decay chain.
The melting point, boiling point, and density of element 107, as well as some other properties,are not known because of the small number of atoms produced.
同位体
There are a total of 10 isotopes of unnilseptium (bohrium). Not all their half-livesare known. However, the ones that are known range from 8.0 milliseconds to 9.8 secondsfor Bh-272, which is the most stable isotope of bohrium and which decays into dubnium-268 through alpha decay. Only one isotope, Uns-261, has a decay mode that involvesboth alpha decay and spontaneous fission. All the others decay by alpha emission.
名前の由来
Named after the scientist Niels Bohr.
来歴
Bohrium is expected to have chemical properties similar to
rhenium. This element was synthesized and unambiguously
identified in 1981 using the Universal Linear Accelerator
(UNILAC) at the Gesellschaft für Schwerionenforschung
(G.S.I.) in Darmstadt, Germany. The discovery team was led
by Armbruster and Münzenberg. The reaction producing the
element was proposed and applied earlier by a Dubna Group
led by Oganessian in 1976. A target of 209Bi was bombarded
by a beam of 54Cr ions. In 1983 experiments at Dubna using
the 157-inch cyclotron, produced 262107 by the reaction 209Bi +
54Cr. The alpha decay of 246Cf, the sixth member in the decay
chain of 262107, served to establish a 1-neutron reaction channel.
The IUPAC adopted the name Bohrium with the symbol
Bh for Element 107 in August 1997. Five isotopes of bohrium
are now recognized. One isotope of bohrium appears to have a
relatively long life of 15 seconds. Work on this relatively longlived
isotope has been performed with the 88-inch cyclotron
at the Lawrence-Berkeley National Laboratory.
使用
None, except for research purposes.
定義
bohrium: Symbol Bh. A radioactivetransactinide element; a.n. 107. Itwas first made in 1981 by Peter Armbrusterand a team in Darmstadt,Germany, by bombarding bismuth-209 nuclei with chromium-54 nuclei.Only a few atoms of bohrium haveever been detected.
危険性
Even though most isotopes of unnilseptium are alpha emitters, there is little radiationhazard because only a few atoms have been produced.
Bohrium 上流と下流の製品情報
原材料
準備製品