lutetium

Lu. Atomic number 71. Electron configuration [Kr] ^{4f145d16s2 .} Lanthanide element in group ³ of the periodic table. One of the rare earth elements of the yttrium group. Atomic weight 174.967(1). Naturally occurring isotopes with mass numbers 175 (97.41(2)%) and 176 (2.59(2)%) exist, but ¹⁷⁶ Lu is a β ^- decay nuclide with a half-life of 3.76× ^1010y . In addition, 150 to 184 radioactive nuclides are known. Due to the difficulty of separating rare earth elements, ytterbium in yttria ore discovered by CG Mosander in 1843 was successively split into new elements, and finally, in 1907, CF Auer von Welsbach and G. Urbain independently separated it as a new element. Urbain, who discovered it early, named it after the Latin name of Paris, Lutetia. It was originally called lutecium, but in 1949, IUPAC decided on lutetium.
Abundance in the earth's crust is 0.3 ppm. It is the least abundant rare earth element, excluding the artificial element Pm. It is a silvery-white metal. It has two modifications: hexagonal α and body-centered cubic β. Its melting point is 1663 °C, its boiling point is 3395 °C. Its density is 9.84 g cm ^-3 (25 °C). Its first ionization energy is 5.426 eV. Its oxidation state is 3. It always forms compounds with Lu ^III . Its oxide and fluoride are colorless and insoluble in water, while its chlorides, bromides, sulfates, and nitrates are colorless and soluble in water. Its salt solutions are also colorless. The electron configuration of Lu ³⁺ is 4f ¹⁴ with a full 4f shell, and it is diamagnetic. It can be used as a catalyst for petroleum cracking, alkylation, and polymerization, but it is rarely used because it is a rare metal and expensive. [CAS 7439-94-3]

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

Lu．原子番号71の元素．電子配置[Kr]4f ¹⁴5d¹6s²の周期表3族ランタノイド元素．希土類元素イットリウム族の一つ．原子量174.967(1)．天然に質量数175(97.41(2)％)と176(2.59(2)％)の同位体が存在するが，¹⁷⁶Luは半減期3.76×10¹⁰ y の β^－ 崩壊核種．このほか，150から184の放射性核種が知られている．希土類分離の難しさから，1843年のC.G. Mosanderの鉱石イットリア中のイッテルビウムが，次々に新しい元素に分割され，最終的に1907年，C.F.Auer von Welsbach(ウェルスバッハ)とG. Urbain(ユルバン)が独立に，新元素として分離した．発表が早かったユルバンがパリのラテン語名Lutetiaから命名した．当初はluteciumであったが，1949年，IUPACがlutetiumと決定した．
地殻中の存在度0.3 ppm．希土類中で人工元素Pmを除いて存在度がもっとも低い．銀白色の金属．六方晶のα，体心立方のβの2変態がある．融点1663 ℃，沸点3395 ℃．密度9.84 g cm^－3(25 ℃)．第一イオン化エネルギー5.426 eV．酸化数3．つねに Lu^Ⅲで化合物をつくる．酸化物，フッ化物は無色で水に不溶，塩化物，臭化物，硫酸塩，硝酸塩も無色で，水に可溶．塩の溶液も無色．Lu^3＋ の電子配置は4f殻充満の4f ¹⁴で反磁性である．石油クラッキング用触媒，アルキル化，重合触媒などに使えるが，希少金属で高価であるため，ほとんど用いられない．[CAS 7439-94-3]

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