Lutetium, Lu, Atomic number 71


Lutetium is a chemical element with the element symbol Lu and atomic number 71. In the periodic table it is in the group of lanthanides and is thus also one of the rare earth metals.
Lutetium was 1905 by three scientists independently discovered: Carl Auer von Welsbach,, Charles James and the Frenchman Georges Urbain, if, after the Roman name of Paris, Lutetia, Named. In the German speaking area until it was 1949 mostly as Cassiopeium (chemical symbol Cp) designated.
In nature, only in lutetium compounds. Lutetiumhaltige minerals are of low concentration:
Monazite (This,The,Th,Nd,And)PO4 (Lu content < 0,01 %)


After an extensive separation of the other Lutetiumbegleiter, the oxide with hydrogen fluoride to Lutetiumfluorid reacted. Subsequently, this reduced with calcium to form calcium fluoride to the metallic lutetium. Separation of remaining calcium residues and impurities occur in an additional remelting in vacuo.

Special features

The silver-gray metal is very soft, stretchable and malleable. In dry air is very stable lutetium, in moist air, it goes to gray. At higher temperatures, it burns Lu2O3 the sesquioxide. With water it reacts very slowly with evolution of hydrogen to hydroxide. In mineral acids it dissolves with the formation of hydrogen on.
In its compounds it is the oxidation state +3 before, the Lu3 ions in water to form colorless solutions.


Lutetium is used in scintillator crystals for positron emission tomography. One of the most prominent examples is doped with cerium Lutetiumoxyorthosilicat (LSO). The radionuclide 177Lu can be used as a therapy against neuroendocrine tumors.
For lutetium has not yet found any biological function.
Lutetium and Lutetiumverbindungen have low toxicity. The metal dusts are fire- and potentially dangerous, Like many others.

Name, Symbol

Atomic number

Lutetium, Lu, 7167
Series Lanthanides
group, Period, Block The, 6, f
Appearance silvery white
CAS-Nummer 7439-94-3
Mass fraction of element 0,7 ppm
Atomic mass 174,967 you
Atomradius 175 pm
Kovalenter Radius 187 pm
Elektronenkonf. [Car] 4f(14) 5d(1) 6s2
1. Ionization 523,5 KJ / mol
2. Ionization 1340 KJ / mol
3. Ionization 2022,3 KJ / mol
Physical State fixed
Crystal structure hexagonal
Density 9,84 g/cm3 (25 ° C)
Magnetism paramagnetisch (χm = 0,0)
Melting point 1925 K (1652 C)
Boiling point 3675 K (3402 C)
Molar Volume 17,78 * 10(-6)m(3)/mol
Heat of vaporization 415 KJ / mol
Schmelzwärme 22,0 KJ / mol
Electrical conductivity 1,72*10(6) A/(V * m)
Thermal conductivity 16 W /(m*K)
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