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General Info
Atomic Symbol Atomic symbol::Tb
Atomic Number Atomic number::65
Atomic Weight Atomic weight::158.9 g/mol
Chemical series Lanthanides
Terbium sample.jpg
Group, Period, Block n/a, 11, f
Electron configuration [Xe] 6s2
Electrons per shell 2,8,18,27,8,2
Electron shell terbium.png
CAS number CAS number::7440-27-9
Physical properties
Phase solid
Density Density::8.27 g/ml
Melting point Melting point::1360.0°C
Boiling point Boiling point::3041.0°C
Isotopes of Terbium
iso NA half-life DT DE (MeV) DP
136Tb unknown β+ 12056.keV 136Gd
137Tb unknown 0.6s p 759.keV 137Gd
137Tb unknown 0.6s β+ 9187.keV 137Gd
138Tb 100% 0.8s β+ 11125.keV 138Gd
138Tb none 0.8s p 293.keV 138Gd
139Tb 100% 1.6s β+ 8340.keV 139Gd
139Tb none 1.6s β+p N/A 139Gd
140Tb 100% 2.4s β+ 10278.keV 140Gd
140Tb 0.26% 2.4s β+p N/A 140Gd
141Tb 100.% 3.5s β+ 7661.keV 141Gd
142Tb 100.% β+ 8878.keV 142Gd
142Tb 0.0022% β+p N/A 142Eu
143Tb 100% 12.s β+ 6776.keV 143Gd
144Tb 100% 1.s β+ 8369.1keV 144Gd
144Tb unknown 1.s β+p N/A 144Eu
145Tb unknown 20.m β+ 6024.3keV 145Gd
146Tb 100.% 8.s β+ 7301.6keV 146Gd
147Tb 100% 1.64h β+ 3588.8keV 147Gd
148Tb 100% 1.h β+ 4713.2keV 148Gd
149Tb 83.3% 4.11667h β+ 2615.28keV 149Gd
149Tb 16.7% 4.11667h α 4077.54keV 149Eu
150Tb 100% 3.472h β+ 3636.03keV 150Gd
150Tb 0.05% 3.472h α 3586.82keV 150Gd
151Tb 100% 17.6089h β+ 1543.19keV 151Gd
151Tb 0.0095% 17.6089h α 3496.06keV 151Gd
152Tb 100% 0.729d β+ 2967.8keV 152Gd
152Tb 7.×10-7% 0.729d α 3153.4keV 152Gd
153Tb 100% 2.338d β+ 547.41keV 153Gd
154Tb 100% 0.8958d β+ 2529.keV 154Gd
154Tb .1% 0.8958d β- 236.2keV 154Gd
155Tb 100% 5.32d ϵ 822.7keV 155Gd
156Tb 100% 5.347d β+ 1422.48keV 156Gd
156Tb unknown 5.347d β- 432.31keV 156Gd
157Tb 100% 69.8y ϵ 60.052keV 157Gd
158Tb 83.4% 180 y β+ 197.335keV 158Dy
158Tb 16.6% 180 y β− 934.89keV 158Dy
159Tb 100% 159Tb is stable with 94 neutrons.
160Tb 100% 72.34d β- 1835.13keV 160Gd
161Tb 100% 6.9062d β- 592.95keV 161Gd
162Tb 100% 7.667m β- 2505.5keV 162Dy
163Tb 100% 19.5m β- 1785.09keV 163Dy
164Tb 100% 3.m β- 3890.keV 164Dy
165Tb 100% 2.117m β- 2959.keV 165Dy
166Tb 100% 25.6s β- 4830.keV 166Dy
167Tb 100% 19.s β- 4093.keV 167Dy
168Tb 100% 8.2s β- 6065.keV 168Dy
169Tb unknown 2.s β- 5507.keV 169Dy
170Tb unknown 3.s β- 7322.keV 170Dy
171Tb unknown 0.5s β- 6614.keV 171Gd
All properties are for STP unless otherwise stated.

Terbium is a lanthanide, meaning it is a rare earth metal. It is soft and silver-grey. Its ability to be sliced with a knife gives hint of it's malleability and ductility. It has many interesting uses. Being used in areas such as the production of energy-saving light bulbs to cancer treatment, this element is not one to be overlooked. Its magnetic qualities even give way into new forms of nanotechnology.


Chemical Properties

A small piece of terbium dissolved in 25% acetic acid.

Terbium is relatively stable in earth's atmosphere.[1] However, it does react slowly with water and dissolves in acids. [2]

  • Thermal conductivity: 11.1 J/m-sec-deg
  • Electrical conductivity: 8.8 1/mohm-cm
  • Polarizability: 25.5 A^3 [3]

Physical Properties

After being dissolved in acid, small crystals of terbium compounds remain, when the acid evaporates.

Terbium is a silver-grey metal. It is malleable, ductile, and can be cut with a knife. [1]

  • The density of Terbium at 293 K is 8.27 g/cm3.
  • Terbium's boiling point is 3041.0 °C (3314.15 K, 5505.8 °F).
  • Terbium's melting point is 1360.0 °C (1633.15 K, 2480.0 °F).[4]
  • Heat of fusion: 10.80 kJ/mol
  • Electron affinity: 50 kJ/mole
  • Electronegativity: 1.21
  • Specific heat: 0.18 J/gK
  • Heat of vaporization: 330.90 kJ/mol
  • 1st ionization energy: 564.7 kJ/mole
  • 2nd ionization energy: 1112 kJ/mole
  • 3rd ionization energy: 2114 kJ/mole

Terbium's atomic weight is 158.9254. The atomic structure of Terbium is hexagonal and tightly packed. [3]


Terbium is available commercially. It can be made in the laboratory, but it is difficult to isolate in its pure metal form. The lanthanides are normally found within certain minerals such as xenotime, monazite, and bastnaesite. The first two of the three are named orthophosphate minerals (LnPO4) and the third is a fluoride carbonate (LnCO3F). Even-numbered lanthanides are the more commonly found minerals. It is more difficult to remove terbium from monazite due to the presence of thorium, a radioactive product. Terbium is not always required to be fully removed from a compound, however, if full separation is called for, it can be very difficult to complete. Terbium is initially extracted as salts from the ore by extraction with the use of sulfuric acid (H2SO4), hydrochloric acid (HCl), and sodium hydroxide (NaOH).
Terbium sulfate (Tb2(SO4)3),a white salt

Modern techniques of purification involve selective complexation techniques, solvent extractions, and ion exchange chromatography. Pure terbium can also be contrived though the reduction of TbF3 by the use of calcium metal.

    Failed to parse (lexing error): 2TbF3 + 3Ca → 2Tb + 3CaF2

Other calcium halides would work well, but the product CaF2 is easier to handle under the reaction conditions (50°C above the melting point of the element in an argon atmosphere). In this following table, ppb stands for parts per billion (1 billion =109).

It is listed in weight and in numbers of atoms. Values are difficult to determine so these numbers are not exact and should not be considered so.

Location ppb by weight ppb by atoms
Universe 0.5 0.004
Sun 0.1 30.001
Meteorite (carbonaceous) 40 5
Sea Water 0.00014 0.000005
Stream 0.008 0.0001
Human no data no data

[1] Terbium is present in the bones and kidneys of both humans and animals.[5] Although Terbium is classified as a rare earth element, this term is misleading. Terbium is actually more prevalent than elements such as silver and mercury. Early chemists gave such elements the rare earth metal title due to the fact that they were hard to separate from other elements, thus they were rarely used. Terbium is one of the rarest of the lanthanides. It ranks around 55th among the elements in the Earth's crust. It's abundance can be compared to molybdenum and tungsten. [2]


Terbium is used in X-ray machines and in cancer treatment.

Elements can have a different number of neutrons. These different possible versions of the element are called isotopes.[6] The only isotope of Terbium that occurs in nature is Terbium-159 ,however, there are many known radioactive isotopes of Terbium. In a radioactive isotope, the particles break apart and give off some form of radiation. The seventeen radioactive isotopes range from Terbium-147-158 and from 160-164. Terbium-149, for example, is used in medicine. The isotope is injected directly into cancer cells in the body. The radiation of Terbium-149 travels a short distance, so it can kill the cancer cells and damage few healthy ones. Therefore this isotope is a safer option than other radioactive sources.[2]

[7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39] [40] [41] [42]


Terbium is used to create a yellow/green color in TV sets.
The most common use of terbium and its compounds are generally in its phosphors. A phosphor gives off light when it is struck by an electron. Television screens are coated with different kinds of phosphors on the back. When electrons inside the television tubes strike the phosphors, they give off different colors of light. Phosphors containing terbium gives off green light.
Terbium sulfate glows green when exposed to ultraviolet light.
They are also used in X-ray screens to create clear pictures.[2] Terbium's phosphorescent qualities allows for a smaller amount of time under an X-ray, causing less tissue damage.[5] Fuel cells are manufactured using terbium. Terbium can use chemical reactions to create electricity, thus it is a fuel cell. Fuel cells, in the future, will be used as a source of electricity. Terbium fuel cells operate very efficiently at high temperatures. [2] Terbium is also used in many magnetic devices. When you add it to certain alloys it forms magnetic devices which shrink or grow based on the strength and form of magnetic energy used. This is called magnetostrictive behavior. This has many technological uses. This could be used for small "motors" or "switches" in future nanotechnology. Terbium can also be used to stain cells which helps in certain laboratory experiments. It is also used in energy saving light bulbs due to its phosphorous qualities when used with the mercury discharge found in florescent strips.[5]

Terbium-149 radiation travels a short distance, so it can kill cancer cells and damage few healthy cells in cancer treatment. This is a safer option than other radioactive sources.[2]

Discovery and History

Memorial plaque of the ASM International society at the entrance of Ytterby mine where the rare earth metals ytterbium, yttrium, terbium, and Erbium were discovered.

Terbium was one element found during the great element hunt of the 1840s. In 1787, a Swedish army lieutenant, Carl Axel Arrhenius (1757-1824), encountered a strange black rock near the town of Ytterby, Sweden. Arrhenius gave this find to his chemist friend, Johan Gadolin (1760-1852). Gadolin analysed the rock, first finding an entire new mineral he named Yttria, after Ytterby. Later on, in 1843, Carl Gustav Mosander, another Swedish chemist, demonstrated that Yttria was really a mix of three minerals. He named them erbia, terbia, and yttria. The ending -a on these names indicates they are minerals found in the earth. This ending also usually refers to the presence of oxygen combined to other elements. However, due to the lack of technology, Mosanders research was unusually long and complicated. Many future chemists even mixed up erbia and terbia, due to lack of proper equipment. Mosander is given credit for discovering Terbium, however in 1886, Jean-Charles-Galissard de Marignac, a Frech chemist was the first to prepare pure terbium.[2]



  1. 1.0 1.1 1.2 Terbium: the essentials by Mark Winter, The University of Sheffield and WebElements Ltd, UK. 1993,
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Unknown author. Chemistry Explained 11/26/10
  3. 3.0 3.1 Unknown. Chemicool Terbium Element Facts 11/26/10
  4. Bentor, Yinon. Chemical - Terbium. Nov. 26, 2010
  5. 5.0 5.1 5.2 Terbium - Periodic Table of Videos The University of Nottingham Brady Haran 2010
  6. Isotopes, 11/26/10
  7. Periodic Wolfram Research, Inc.Isotope Tb-136
  8. Periodic Wolfram Research, Inc.Isotope Tb-137
  9. Periodic Wolfram Research, Inc.Isotope Tb-138
  10. Periodic Wolfram Research, Inc.Isotope Tb-139
  11. Periodic Wolfram Research, Inc.Isotope Tb-140
  12. Periodic Wolfram Research, Inc.Isotope Tb-141
  13. Periodic Wolfram Research, Inc.Isotope Tb-142
  14. Periodic Wolfram Research, Inc.Isotope Tb-143
  15. Periodic Wolfram Research, Inc.Isotope Tb-144
  16. Periodic Wolfram Research, Inc.Isotope Tb-145
  17. Periodic Wolfram Research, Inc.Isotope Tb-146
  18. Periodic Wolfram Research, Inc.Isotope Tb-147
  19. Periodic Wolfram Research, Inc.Isotope Tb-148
  20. Periodic Wolfram Research, Inc.Isotope Tb-149
  21. Periodic Wolfram Research, Inc.Isotope Tb-150
  22. Periodic Wolfram Research, Inc.Isotope Tb-151
  23. Periodic Wolfram Research, Inc.Isotope Tb-152
  24. Periodic Wolfram Research, Inc.Isotope Tb-153
  25. Periodic Wolfram Research, Inc.Isotope Tb-154
  26. Periodic Wolfram Research, Inc.Isotope Tb-155
  27. Periodic Wolfram Research, Inc.Isotope Tb-156
  28. Periodic Wolfram Research, Inc.Isotope Tb-157
  29. Periodic Wolfram Research, Inc.Isotope Tb-158
  30. Periodic Wolfram Research, Inc.Isotope Tb-159
  31. Periodic Wolfram Research, Inc.Isotope Tb-160
  32. Periodic Wolfram Research, Inc.Isotope Tb-161
  33. Periodic Wolfram Research, Inc.Isotope Tb-162
  34. Periodic Wolfram Research, Inc.Isotope Tb-163
  35. Periodic Wolfram Research, Inc.Isotope Tb-164
  36. Periodic Wolfram Research, Inc.Isotope Tb-165
  37. Periodic Wolfram Research, Inc.Isotope Tb-166
  38. Periodic Wolfram Research, Inc.Isotope Tb-167
  39. Periodic Wolfram Research, Inc.Isotope Tb-168
  40. Periodic Wolfram Research, Inc.Isotope Tb-169
  41. Periodic Wolfram Research, Inc.Isotope Tb-170
  42. Periodic Wolfram Research, Inc.Isotope Tb-171

Additional Information