Terbium is a soft, silvery rare earth metal with element symbol Tb and atomic number 65. It isn't found free in nature, but it occurs in many minerals and is used in green phosphors and solid state devices. Get terbium facts and figures. Learn about the properties of this important element:
Terbium Basic Facts
Atomic Number: 65
Symbol: Tb
Atomic Weight: 158.92534
Discovery: Carl Mosander 1843 (Sweden)
Electron Configuration: [Xe] 4f9 6s2
Element Classification: Rare Earth (Lanthanide)
Word Origin: Named after Ytterby, a village in Sweden.
Uses: Terbium oxide is the green phosphor found in color television tubes, trichromatic lighting, and fluorescent lamps. Its phosphorescence also makes it used as a probe in biology Terbium is used to dope calcium tungstate, calcium fluoride, and strontium molybdate to make solid state devices. It is used to stabilize crystals in fuel cells. The element occurs in many alloys. One alloy (Terfenol-D) expands or contracts when exposed to a magnetic field.
Biological Role: Terbium serves no known biological role. Like other lanthanides, the element and its compounds exhibit low to moderate toxicity.
![This is a photo of terbium, one of the rare earth elements. Terbium is a soft silvery-white metal.](https://www.thoughtco.com/thmb/b7xQUwJA2FrsS_RvqstWY9LHX0s=/1500x0/filters:no_upscale():max_bytes(150000):strip_icc()/terbium-56a12c6f3df78cf772682044.jpg)
Terbium Physical Data
Density (g/cc): 8.229
Melting Point (K): 1629
Boiling Point (K): 3296
Appearance: soft, ductile, silvery-gray, rare-earth metal
Atomic Radius (pm): 180
Atomic Volume (cc/mol): 19.2
Covalent Radius (pm): 159
Ionic Radius: 84 (+4e) 92.3 (+3e)
Specific Heat (@20°C J/g mol): 0.183
Evaporation Heat (kJ/mol): 389
Pauling Negativity Number: 1.2
First Ionizing Energy (kJ/mol): 569
Oxidation States: 4, 3
Lattice Structure: Hexagonal
Lattice Constant (Å): 3.600
Lattice C/A Ratio: 1.581
Sources
- Emsley, John (2011). Nature's building blocks: An A-Z Guide to the Elements. Oxford University Press. ISBN 978-0-19-960563-7.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- Hammond, C. R. (2004). The Elements, in Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN 978-0-8493-0485-9.
- Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.