lawrencium

Lr. An element with atomic number 103. It is an actinide element in group 3 of the periodic table with the electron configuration [Rn]5f ¹⁴ 6d ¹ 7s ^2. It was named after EO Lawrence, who invented the cyclotron. In March 1961, A. Ghiorso and others at the University of California (Berkeley) announced that they had synthesized a nuclide with mass number 257 that decays by alpha decay with a half-life of 8 s by bombarding 3 mg of a mixture of ^{249, 250} , 251, and 252 Cf with ¹⁰ B or ¹¹ B ions accelerated by a heavy ion linear accelerator (HILAC). In 1965-1967, GN Flerov and others at the Joint Institute for Nuclear Research (JINR) in Dubna, Soviet Union (at the time) reported that they could not confirm this nuclide. In 1970, the Berkeley group conducted a solvent extraction experiment using only 10 atoms of a nuclide with mass number 256, and concluded that Lr behaves more like a trivalent ion of an actinide element with a lower atomic number than No2 ⁺ , which is the previous element. Oxidation numbers 2 and 3. Currently, there are 15 known isotopic nuclides in the range of 252 to 266. The latest data shows that the alpha-decay nuclide with mass number 256 has a half-life of 27 s. ²⁶¹ Lr 39 min, ²⁶² Lr 4 h (both spontaneous fission). [CAS 22537-19-5]

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

Lr．原子番号103の元素．電子配置[Rn]5f ¹⁴6d¹7s²の周期表3族アクチノイド元素．サイクロトロンを発明したE.O. Lawrenceにちなんで命名された．1961年3月，カリフォルニア大学(バークレー校)のA. Ghiorsoらは，^{249,250,251,252}Cf の混合物3 mg を重イオン線形加速器(HILAC)で加速した ¹⁰B または ¹¹B イオンで衝撃し，半減期8 s でα崩壊する質量数257の核種を合成したと発表した．1965～1967年，ソビエト(当時)・ドゥブナの原子核合同研究所(JINR)のG.N. Flerov(フレロフ)らは，この核種を確認できないと報告した．1970年，バークレーグループは質量数256の核種のわずか10原子を使って溶媒抽出実験を行い，Lrは直前の No^2＋ より，原子番号の若いアクチノイド元素の三価イオンに似たふるまいをすると結論した．酸化数2，3．現在，知られている同位体核種は，252～266の範囲に15種．最新のデータでは，質量数256のα崩壊核種は半減期27 s．²⁶¹Lr 39 min，²⁶²Lr 4 h(ともに自発核分裂)．[CAS 22537-19-5]

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