THULIUM

Introduction

Atomic Number: 69
Group: None
Atomic Weight: 168.93421
Period: 6
CAS Number: 7440-30-4

Classification

Chalcogen
Halogen
Noble Gas
Lanthanoid
Actinoid
Rare Earth Element
Platinum Group Metal
Transuranium
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)

Description • Uses/Function

Discovered in 1879 by Cleve. Thulium occurs in small quantities along with other rare earths in a number of minerals. It is obtained commerciallyfrom monazite, which contains about 0.007% of the element. Thulium is the least abundant of the rare earth elements, but with new sources recentlydiscovered, it is now considered to be about as rare as silver, gold, or cadmium. Ion-exchange and solvent extraction techniques have recently permittedmuch easier separation of the rare earths, with much lower costs. Only a few years ago, thulium metal was not obtainable at any cost; in 1996 the oxidecost $20/g. Thulium metal powder now costs $60/g (99.9%). Thulium can be isolated by reduction of the oxide with lanthanum metal or by calciumreduction of the anhydrous fluoride. The pure metal has a bright, silvery luster. It is reasonably stable in air, but the metal should be protected frommoisture in a closed container. The element is silver-gray, soft, malleable, and ductile, and can be cut with a knife. Thirty eight isotopes and isomersare known, with atomic masses ranging from 146 to 176. Natural thulium, which is 100% 169Tm, is stable. Because of the relatively high price of themetal, thulium has not yet found many practical applications. 169Tm bombarded in a nuclear reactor can be used as a radiation source in portable Xrayequipment. 171Tm is potentially useful as an energy source. Natural thulium also has possible use in ferrites (ceramic magnetic materials) usedin microwave equipment. As with other lanthanides, thulium has a low-to-moderate acute toxic rating. It should be handled with care. 1

Physical Properties

Melting Point:2*  1545 °C = 1818.15 K = 2813 °F
Boiling Point:2* 1950 °C = 2223.15 K = 3542 °F
Sublimation Point:2 
Triple Point:2 
Critical Point:2 
Density:3  9.32 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration:  *[Xe] 6s2 4f13
Block: f
Highest Occupied Energy Level: 6
Valence Electrons: 2

Quantum Numbers:

n = 4
ℓ = 3
m = 2
ms = -½

Bonding

Electronegativity (Pauling scale):4 1.25
Electropositivity (Pauling scale): 2.75

Ionization Potential   eV 5  kJ/mol  
1 6.18431    596.7
Ionization Potential   eV 5  kJ/mol  
2 12.05    1162.6
Ionization Potential   eV 5  kJ/mol  
3 23.68    2284.8
4 42.7    4119.9

Thermochemistry

Specific Heat: 0.160 J/g°C 6 = 27.029 J/mol°C = 0.038 cal/g°C = 6.460 cal/mol°C
Thermal Conductivity: 16.8 (W/m)/K, 27°C 7
Heat of Fusion: 16.84 kJ/mol 8 = 99.7 J/g
Heat of Vaporization: 191 kJ/mol 9 = 1130.6 J/g
State of Matter Enthalpy of Formation (ΔHf°)10 Entropy (S°)10 Gibbs Free Energy (ΔGf°)10
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 17.69 74.01496 0 0
(g) 55.5 232.212 45.41 189.99544 47.2 197.4848

Isotopes

Nuclide Mass 11 Half-Life 11 Nuclear Spin 11 Binding Energy
145Tm 144.97007(43)# 3.1(3) μs (11/2-) 1,144.30 MeV
146Tm 145.96643(43)# 240(30) ms (6-) 1,161.69 MeV
147Tm 146.96096(32)# 0.58(3) s 11/2- 1,169.76 MeV
148Tm 147.95784(43)# 0.7(2) s (10+) 1,187.15 MeV
149Tm 148.95272(32)# 0.9(2) s (11/2-) 1,195.22 MeV
150Tm 149.94996(21)# 3# s (1+) 1,212.60 MeV
151Tm 150.945483(22) 4.17(10) s (11/2-) 1,220.67 MeV
152Tm 151.94442(8) 8.0(10) s (2#)- 1,228.75 MeV
153Tm 152.942012(20) 1.48(1) s (11/2-) 1,236.82 MeV
154Tm 153.941568(15) 8.1(3) s (2-) 1,244.89 MeV
155Tm 154.939199(14) 21.6(2) s (11/2-) 1,262.27 MeV
156Tm 155.938980(17) 83.8(18) s 2- 1,270.35 MeV
157Tm 156.93697(3) 3.63(9) min 1/2+ 1,278.42 MeV
158Tm 157.936980(27) 3.98(6) min 2- 1,286.49 MeV
159Tm 158.93498(3) 9.13(16) min 5/2+ 1,294.56 MeV
160Tm 159.93526(4) 9.4(3) min 1- 1,302.63 MeV
161Tm 160.93355(3) 30.2(8) min 7/2+ 1,310.70 MeV
162Tm 161.933995(28) 21.70(19) min 1- 1,318.77 MeV
163Tm 162.932651(6) 1.810(5) h 1/2+ 1,326.85 MeV
164Tm 163.93356(3) 2.0(1) min 1+ 1,334.92 MeV
165Tm 164.932435(4) 30.06(3) h 1/2+ 1,342.99 MeV
166Tm 165.933554(13) 7.70(3) h 2+ 1,351.06 MeV
167Tm 166.9328516(29) 9.25(2) d 1/2+ 1,359.13 MeV
168Tm 167.934173(3) 93.1(2) d 3+ 1,367.20 MeV
169Tm 168.9342133(27) STABLE 1/2+ 1,375.27 MeV
170Tm 169.9358014(27) 128.6(3) d 1- 1,383.34 MeV
171Tm 170.9364294(28) 1.92(1) a 1/2+ 1,391.42 MeV
172Tm 171.938400(6) 63.6(2) h 2- 1,399.49 MeV
173Tm 172.939604(5) 8.24(8) h (1/2+) 1,407.56 MeV
174Tm 173.94217(5) 5.4(1) min (4)- 1,406.31 MeV
175Tm 174.94384(5) 15.2(5) min (1/2+) 1,414.39 MeV
176Tm 175.94699(11) 1.85(3) min (4+) 1,422.46 MeV
177Tm 176.94904(32)# 90(6) s (7/2-) 1,430.53 MeV
178Tm 177.95264(43)# 30# s 1,429.29 MeV
179Tm 178.95534(54)# 20# s 1/2+# 1,437.36 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 11

Abundance

Earth - Source Compounds: phosphates 12
Earth - Seawater: 0.00000017 mg/L 13
Earth -  Crust:  0.52 mg/kg = 0.000052% 13
Earth -  Total:  35 ppb 14
Mercury -  Total:  27 ppb 14
Venus -  Total:  37 ppb 14
Chondrites - Total: 0.031 (relative to 106 atoms of Si) 15

Compounds

Safety Information


Material Safety Data Sheet - ACI Alloys, Inc.

For More Information

External Links:

Magazines:
(1) Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, pp 136-145.

Sources

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:32.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(4) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(10) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(11) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(12) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(14) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(15) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.