ラザホージウム

ラザホージウム 化学特性,用途語,生産方法

• 解説

  ラザホージウム，原子番号104の元素．電子配置[Rn]5f146d27s2の周期表4族元素．周期表でハフニウムの下に位置する(エカハフニウム)．103番元素ローレンシウムでアクチノイド系列が終了するので，最初の超アクチノイド元素である．IUPACは，105番元素にソビエトグループにちなんだ元素名を採用したので，104番元素にはこれを採択した(1997年)．質量数253～268の同位体核種が知られており，261Rf は半減期65 s で 257No にα崩壊する．265Rf が半減期13 h という報告もある．

• 物理的性質

  The chemical and physical properties of Unq (or rutherfordium) are homologous with theelement hafnium (72Hf ), located just above it in group 4 (IVB) in the periodic table. It wasfirst claimed to be produced artificially by the Joint Institute for Nuclear Research (JINR)located in Dubna, Russia. The Russian scientists used a cyclotron that smashed a target ofplutonium-242 with very heavy ions of neon-22, resulting in the following reaction: ₉₄Pu-242 + ₁₀Ne-22 →₁₀₄Unq-260 + 4₀n-1 (alpha radiation). The Russians named Unq-260 “kurchatovium”(Ku-260) for the head of their center, Ivan Kurchatov. (See details in the next section,“History.”).

• 同位体

  There are a total of 15 isotopes for rutherfordium, ranging from Rf-253 to Rf-264. Their half-lives range from 23 microseconds to 10 minutes. They are all artificiallymade, radioactive, and unstable. Their decay modes are a combination of alpha decayand spontaneous fission (SF).

• 名前の由来

  Named by the transition naming system of the IUPAC (unnilquadium) and later named after the New Zealand scientist Ernest Rutherford (rutherfordium).

• 使用

  There are no uses for unnilquadium (rutherfordium), except for high-energy nuclear-particleresearch.

• 定義

  A radioactive metal not found naturally on earth. It is the first transactinide metal. Atoms of rutherfordium are produced by bombarding ²⁴⁹Cf with 12C or by bombarding ²⁴⁸Cm with 18O. Symbol: Rf; m.p. 2100°C (est.); b.p. 5200°C (est.); r.d. 23 (est.); most stable isotope ²⁶¹Rf (half-life 65s).

• 危険性

  The hazards of unnilquadium are the same as for any radioactive element. Since there areonly a few atoms with short half-lives produced at a time in scientific laboratories, there islittle danger to the public.

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