Ytterbium - Lutetium - Hafnium


Name, Symbol, Number Lutetium, Lu, 71
Chemical series Lanthanides
Group, Period, Block 3, 6, d
Density, Hardness 9841 kg/m3, __
Appearance Silvery white
Missing image

Atomic properties
Atomic weight 174.967 u
Atomic radius (calc.) 175 (217) pm
Covalent radius 160 pm
van der Waals radius no data
Electron configuration [Xe]4f14 5d1 6s2
e- 's per energy level 2, 8, 18, 32, 9, 2
Oxidation states (Oxide) 3 (weak base)
Crystal structure hexagonal
Physical properties
State of matter solid (__)
Melting point 1925 K (3006 ?F)
Boiling point 3675 K (6156 ?F)
Molar volume 17.78 ×10-6 m3/mol
Heat of vaporization 355.9 kJ/mol
Heat of fusion 18.6 kJ/mol
Vapor pressure 2460 Pa at 1936 K
Velocity of sound no data
Electronegativity 1.27 (Pauling scale)
Specific heat capacity 150 J/(kg*K)
Electrical conductivity 1.85 106/m ohm
Thermal conductivity 16.4 W/(m*K)
1st ionization potential 523.5 kJ/mol
2nd ionization potential 1340 kJ/mol
3rd ionization potential 2022.3 kJ/mol
4th ionization potential 4370 kJ/mol
5th ionization potential 6445 kJ/mol
Most stable isotopes
iso NA half-life DM DE MeV DP
173Lu {syn.} 1.37 y ε 0.671 173Yb
174Lu {syn.} 3.31 y ε 1.374 174Yb
175Lu 97.41% Lutetium is stable with 104 neutrons
176Lu 2.59% 3.78 E10 y β- 1.193 176Hf
SI units & STP are used except where noted.

Lutetium is a chemical element in the periodic table that has the symbol Lu and atomic number 71. A metallic element of the rare earth group, lutetium usually occurs in association with yttrium and is sometimes used in metal alloys and as a catalyst in various processes. A strict correlation between periodic table blocks and chemical series for neutral atoms would describe lutetium as a transition metal, but it is commonly considered a lanthanide.

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Notable characteristics and applications

Lutetium is a silvery white corrosion-resistant trivalent metal that is relatively stable in air and is the heaviest and hardest of the rare earth elements.

This element is very expensive to obtain in useful quantities and therefore it has very few commercial uses. However, stable lutetium can be used as catalysts in petroleum cracking in refineries and can also be used in alkylation, hydrogenation, and polymerization applications.


Lutetium (Latin Lutetia meaning Paris) was independently discovered in 1907 by French scientist Georges Urbain and Austrian mineralogist Baron Carol Auer von Welsbach. Both men found lutetium as an impurity in the mineral ytterbia which was thought by Swiss chemist Jean Charles Galissard de Marignac (and most others) to consist entirely of the element ytterbium.

The separation of lutetium from Marignac's ytterbium was first described by Urbain and the naming honor therefore went to him. He chose the names neoytterbium (new ytterbium) and lutecium for the new element but neoytterbium was eventually reverted back to ytterbium and in 1949 the spelling of element 71 was changed to lutetium.

Welsbach proposed the names cassiopium for element 71 (after the constellation Cassiopeia) and albebaranium for the new name of ytterbium but these naming proposals where rejected (although many German scientists still call element 71 cassiopium).


Found with almost all other rare-earth metals but never by itself, lutetium is very difficult to separate from other elements and is the least abundant of all naturally-occurring elements. Consequently, it is also one of the most expensive metals, costing about six times as much per gram as Gold.

The principal commercially viable ore of lutetium is the mineral monzonite [(Ce, La, etc.)PO4] which contains 0.003% of the element. Pure lutetium metal has only relatively recently been isolated and is very difficult to prepare (thus it is one of the most rare and expensive of the rare earth metals). It is separated from other rare earth elements by ion exchange (reduction of anhydrous LuCl3 or LuF3 by either an alkali metal or alkaline earth metal).


Naturally occurring lutetium is composed of 1 stable isotope Lu-175 (97.41% natural abundance). 33 radioisotopes have been characterized, with the most stable being Lu-176 with a half-life of 3.78 × 1010 years (2.59% natural abundance), Lu-174 with a half-life of 3.31 years, and Lu-173 with a half-life of 1.37 years. All of the remaining radioactive isotopes have half-lifes that are less than 9 days, and the majority of these have half lifes that are less than a half an hour. This element also has 18 meta states, with the most stable being Lu-177m (t? 160.4 days), Lu-174m (t? 142 days) and Lu-178m (t? 23.1 minutes).

The isotopes of lutetium range in atomic weight from 149.973 (Lu-150) to 183.961 (Lu-184). The primary decay mode before the most abundant stable isotope, Lu-175, is electron capture (with some alpha and positron emission), and the primary mode after is beta emission. The primary decay products before Lu-175 are element 70 (ytterbium) isotopes and the primary products after are element 72 (hafnium) isotopes.


Fluoride: LuF3, Chloride: LuCl3, Bromide: LuBr3, Iodide: LuI3, Oxide: Lu2O3, Sulfide: Lu2S3, Telluride: Lu2Te3, Nitride: LuN


Like other rare-earth metals lutetium is regarded as having a low toxicity rating but it and especially its compounds should be handled with care nonetheless. Metal dust of this element is a fire and explosion hazard. Lutetium plays no biological role in the human body but is thought to help stimulate metabolism.


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