TERBIUM

Introduction

Atomic Number: 65
Group: None
Atomic Weight: 158.92534
Period: 6
CAS Number: 7440-27-9

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 by Mosander in 1843. Terbium is a member of the lanthanide or “rare earth” group of elements. It is found in cerite, gadolinite, and other mineralsalong with other rare earths. It is recovered commercially from monazite in which it is present to the extent of 0.03%, from xenotime, and from euxenite,a complex oxide containing 1% of more of terbia. Terbium has been isolated only in recent years with the development of ion-exchange techniquesfor separating the rare-earth elements. As with other rare earths, it can be produced by reducing the anhydrous chloride or fluoride with calcium metalin a tantalum crucible. Calcium and tantalum impurities can be removed by vacuum remelting. Other methods of isolation are possible. Terbium isreasonably stable in air. It is a silver-gray metal, and is malleable, ductile, and soft enough to be cut with a knife. Two crystal modifications exist, witha transformation temperature of 1289°C. Forty one isotopes and isomers are recognized. The oxide is a chocolate or dark maroon color. Sodium terbiumborate is used as a laser material and emits coherent light at 0.546 micrometers. Terbium is used to dope calcium fluoride, calcium tungstate, and strontiummolybdate, used in solid-state devices. The oxide has potential application as an activator for green phosphors used in color TV tubes. It can be usedwith ZrO2 as a crystal stabilizer of fuel cells which operate at elevated temperature. Few other uses have been found. The element is priced at about$30/g (99.9%). Little is known of the toxicity of terbium. It should be handled with care as with other lanthanide elements. 1

• "[in] a compact fluorescent lightbulb" 2

Physical Properties

Melting Point:3*  1356 °C = 1629.15 K = 2472.8 °F
Boiling Point:3* 3230 °C = 3503.15 K = 5846 °F
Sublimation Point:3 
Triple Point:3 
Critical Point:3 
Density:4  8.23 g/cm3

* - at 1 atm

Electron Configuration

Electron Configuration:  *[Xe] 6s2 4f9
Block: f
Highest Occupied Energy Level: 6
Valence Electrons: 2

Quantum Numbers:

n = 4
ℓ = 3
m = -2
ms = -½

Bonding

Work Function:5 3.0 eV = 4.806E-19 J

Ionization Potential   eV 6  kJ/mol  
1 5.8638    565.8
Ionization Potential   eV 6  kJ/mol  
2 11.52    1111.5
Ionization Potential   eV 6  kJ/mol  
3 21.91    2114.0
4 39.79    3839.2

Thermochemistry

Specific Heat: 0.182 J/g°C 7 = 28.924 J/mol°C = 0.043 cal/g°C = 6.913 cal/mol°C
Thermal Conductivity: 11.1 (W/m)/K, 27°C 8
Heat of Fusion: 10.8 kJ/mol 9 = 68.0 J/g
Heat of Vaporization: 330.9 kJ/mol 10 = 2082.1 J/g
State of Matter Enthalpy of Formation (ΔHf°)11 Entropy (S°)11 Gibbs Free Energy (ΔGf°)11
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 17.50 73.22 0 0
(g) 92.9 388.6936 48.63 203.46792 83.6 349.7824

Isotopes

Nuclide Mass 12 Half-Life 12 Nuclear Spin 12 Binding Energy
135Tb 0.94(+33-22) ms (7/2-)
136Tb 135.96138(64)# 0.2# s 1,084.10 MeV
137Tb 136.95598(64)# 600# ms 11/2-# 1,101.49 MeV
138Tb 137.95316(43)# 800# ms [>200 ns] 1,109.56 MeV
139Tb 138.94829(32)# 1.6(2) s 11/2-# 1,126.95 MeV
140Tb 139.94581(86) 2.4(2) s 5 1,135.02 MeV
141Tb 140.94145(11) 3.5(2) s (5/2-) 1,143.09 MeV
142Tb 141.93874(32)# 597(17) ms 1+ 1,160.48 MeV
143Tb 142.93512(6) 12(1) s (11/2-) 1,168.55 MeV
144Tb 143.93305(3) ~1 s 1+ 1,176.62 MeV
145Tb 144.92927(6) 20# min (3/2+) 1,194.01 MeV
146Tb 145.92725(5) 8(4) s 1+ 1,202.08 MeV
147Tb 146.924045(13) 1.64(3) h 1/2+# 1,210.15 MeV
148Tb 147.924272(15) 60(1) min 2- 1,218.22 MeV
149Tb 148.923246(5) 4.118(25) h 1/2+ 1,226.29 MeV
150Tb 149.923660(8) 3.48(16) h (2-) 1,234.36 MeV
151Tb 150.923103(5) 17.609(1) h 1/2(+) 1,242.43 MeV
152Tb 151.92407(4) 17.5(1) h 2- 1,250.51 MeV
153Tb 152.923435(5) 2.34(1) d 5/2+ 1,258.58 MeV
154Tb 153.92468(5) 21.5(4) h 0(+#) 1,266.65 MeV
155Tb 154.923505(13) 5.32(6) d 3/2+ 1,274.72 MeV
156Tb 155.924747(5) 5.35(10) d 3- 1,282.79 MeV
157Tb 156.9240246(27) 71(7) a 3/2+ 1,290.86 MeV
158Tb 157.9254131(28) 180(11) a 3- 1,298.93 MeV
159Tb 158.9253468(27) STABLE 3/2+ 1,307.00 MeV
160Tb 159.9271676(27) 72.3(2) d 3- 1,315.08 MeV
161Tb 160.9275699(28) 6.906(19) d 3/2+ 1,323.15 MeV
162Tb 161.92949(4) 7.60(15) min 1- 1,331.22 MeV
163Tb 162.930648(5) 19.5(3) min 3/2+ 1,329.97 MeV
164Tb 163.93335(11) 3.0(1) min (5+) 1,338.05 MeV
165Tb 164.93488(21)# 2.11(10) min 3/2+# 1,346.12 MeV
166Tb 165.93799(11) 25.6(22) s 1,354.19 MeV
167Tb 166.94005(43)# 19.4(27) s 3/2+# 1,352.95 MeV
168Tb 167.94364(54)# 8.2(13) s 4-# 1,361.02 MeV
169Tb 168.94622(64)# 2# s 3/2+# 1,369.09 MeV
170Tb 169.95025(75)# 3# s 1,367.84 MeV
171Tb 170.95330(86)# 500# ms 3/2+# 1,375.92 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. 12

Abundance

Earth - Source Compounds: phosphates 13
Earth - Seawater: 0.00000014 mg/L 14
Earth -  Crust:  1.2 mg/kg = 0.00012% 14
Earth -  Total:  54 ppb 15
Mercury -  Total:  41 ppb 15
Venus -  Total:  56 ppb 15
Chondrites - Total: 0.051 (relative to 106 atoms of Si) 16

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 4:31.
(2) - Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, p 140.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(5) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(6) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(12) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(13) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(14) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(15) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(16) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(17) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.