71
  Lu  
174.967000
Lutetium

Name: Lutetium
Symbol: Lu
Atomic Number: 71
Atomic Weight: 174.967000
Family: Rare Earth Elements
CAS RN: 7439-94-3
Description: A silvery white rare earth metal.
State (25C): Solid
Oxidation states: +3

Molar Volume: 17.78 cm3/mole
Valence Electrons: 5d16s2

Boiling Point:  3668K, 3395C, 6143F
Melting Point:
1936K, 1663C, 3025F
Electrons Energy Level:  2, 8, 18, 32, 9, 2
Isotopes: 34 + 1 Stable + 18 meta states
Heat of Vaporization:  355.9 kJ/mol
Heat of Fusion: 18.6 kJ/mol
Density:  9.84 g/cm3 @ 300K
Specific Heat:  0.15 J/gK
Atomic Radius: 2.25
Ionic Radius: 0.848
Electronegativity: 1.27 (Pauling); 1.14 (Allrod Rochow)
Vapor Pressure: 2460 Pa @ 1663C
57
La
138.9
58
Ce
140.1
59
Pr
140.9
60
Nd
144.2
61
Pm
(145)
62
Sm
150.4
63
Eu
152.0
64
Gd
157.3
65
Tb
158.9
66
Dy
162.5
67
Ho
164.9
68
Er
167.3
69
Tm
168.9
70
Yb
173.0
71
Lu
175.0

1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d1 6s2

History

Lutetium (Latin, Lutecia meaning Paris) was independently discovered in 1907-08 by French scientist Georges Urbain and Austrian mineralogist Baron Carl 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 in the 1950s called the element 71 cassiopium).

The refinement of ion exchange methods and their application to the separation of the rare-earths made the separation of lutetium from ytterbium possible. von Welsbach decided to rename ytterbium aldebaranium and picked cassiopium for element 71. Urbain preferred neoytterbium and lutecium. Urbain's choices eventually were accepted, although the prefix was dropped from ytterbium and the spelling of lutecium was eventually changed.

Characteristics

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.

1s2
2s2 2p6
3s2 3p6 3d10
4s2 4p6 4d10 4f14
5s2 5p6 5d1
6s2

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 craking in refineries and can also be used in alkylation, hydrogenation, and polymerization applications.

Occurrence

Found with almost all other rare-earth metals but never by itself, lutetium is very difficult to separate from other 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 rare earth phosphate mineral Monazite: (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 and then obtained in the elemental form by reduction of anhydrous LuCl3 or LuF3 by either an alkali metal or alkaline earth metal.

Applications

Lutetium aluminum garnet (Al5Lu3O12) has been proposed for use as a lens material in high refractive index immersion lithography.

Cerium-doped lutetium oxyorthosilicate (LSO) is currently the preferred compound for detectors in positron emission tomography (PET.)

Compounds

Fluoride Chloride Bromide
LuF3 LuCl3 LuBr3
Iodide Oxide Sulfide
LuI3 Lu22O3 Lu2S3
  Nitride  
  LuN  

Isotopes

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 ytterbium-70 isotopes and the primary products after are element hafnium-72 isotopes.

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Isotope  
Atomic Mass
 
Half-Life
150Lu 149.97323 43 ms
151Lu 150.96758 80.6 ms
152Lu 151.96412 650 ms
153Lu 152.95877 0.9 seconds
154Lu 153.95752 ~1 seconds
154m1Lu   1.12 seconds
155Lu 154.954316 68.6 ms
156Lu 155.95303 494 ms
157Lu 156.950098 6.8 seconds
157mLu   4.79 seconds
158Lu 157.949313 10.6 seconds
159Lu 158.94663 12.1 seconds
159mLu   ~10 seconds
160Lu 159.94603 36.1 seconds
160mLu   40 seconds
161Lu 160.94357 77 seconds
162Lu 161.94328 1.37 minutes
162m1Lu   1.5 minutes
162m2Lu   1.9 minutes
163Lu 162.94118 3.97 minutes
164Lu 163.94134 3.14 minutes
165Lu 164.939407 10.74 minutes
166Lu 165.93986 2.65 minutes
166m1Lu   1.41 minutes
166m2Lu   2.12 minutes
167Lu 166.93827 51.5 minutes
167mLu   >1 minutes
168Lu 167.93874 5.5 minutes
168mLu   6.7 minutes
169Lu 168.937651 34.06 hours
169mLu   160 seconds
170Lu 169.938475 2.012 days
171Lu 170.9379131 8.24 days
171mLu   79 seconds
172Lu 171.939086 6.70 days
172m1Lu   3.7 minutes
173Lu 172.9389306 1.37 years
174Lu 173.9403375 3.31 years
174m1Lu   142 days
175Lu 174.9407718 Stable
176Lu 175.9426863 38.5 x 109 years
176mLu   3.664 hours
177Lu 176.9437581 6.6475 days
177m3Lu   160.44 days
177m4Lu   7 minutes
178Lu 177.945955 28.4 minutes
178mLu   23.1 minutes
179Lu 178.947327 4.59 hours
180Lu 179.94988 5.7 minutes
181Lu 180.95197 3.5 minutes
182Lu 181.95504 2.0 minutes
183Lu 182.95757 58 seconds
184Lu 183.96091 20 seconds

Precautions

Like other rare-earth metals lutetium is regarded as having a low toxcity 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.

 


atom.gif (700 bytes)

Lutetium Data

 

Atomic Structure

Atomic Radius (): 2.25
Atomic Volume: 17.78cm3/mol
Covalent Radius: 1.56
Crystal Structure: Hexagonal
Ionic Radius: 0.848

Chemical Properties

Electrochemical Equivalents: 2.176 g/amp-hr
Electron Work Function: 3.3eV
Electronegativity: 1.27 (Pauling); 1.14 (Allrod Rochow)
Heat of Fusion: 18.6 kJ/mol
First Ionization Potential: 5.4259
Second Ionization Potential: 13.888
Third Ionization Potential: 20.957
Valence Electron Potential (-eV): 50.9
Ionization Energy (eV): 5.426 eV

Physical Properties

Atomic Mass Average: 174.967
Boiling Point: 3668K, 3395C, 6143F
Melting Point: 1936K, 1663C, 3025F
Heat of Vaporization: 355.9kJ/mol
Coefficient of Lineal Thermal Expansion/K-1: 8.12E-6
Electrical Conductivity: 0.0185 106/cm
Thermal Conductivity: 0.164 W/cmK
Density: 9.84 g/cm3 @ 300K
Enthalpy of Atomization: 398 kJ/mole @ 25C
Enthalpy of Fusion: 18.7 kJ/mole
Enthalpy of Vaporization: 355.9 kJ/mole
Molar Volume: 17.78 cm3/mole
Specific Heat: 0.15 J/gK
Vapor Pressure: 2460 Pa @ 1663C
Estimated Crustal Abundance: 810-1 milligrams per kilogram
Estimated Oceanic Abundance: 1.510-7 milligrams per liter