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Terbium - Tb

Chemical properties of terbium - Health effects of terbium - Environmental effects of terbium

Atomic number


Atomic mass

158.92534 g.mol -1

Electronegativity according to Pauling



8.3 g.cm-3 at 20°C

Melting point

1360 °C

Boiling point

3041 °C

Vanderwaals radius


Ionic radius




Electronic shell

[ Xe ] 4f9 6s2

Energy of first ionisation

563.5 kJ.mol -1

Energy of second ionisation

1109.6 kJ.mol -1

Standard potential

- 2.39 V


Carl Mosander in 1843


Terbium is a soft, malleable, ductile, silver-gray metal member of the lanthanide group of the periodic table. It is reasonably stable in air, but it is slowly oxidised and it reacts with cold water.


Terbium is rare and expensive, so it has few commercial uses. Some minor uses are in lasers, semiconductor devices, and phosphorous in colour television tubes. It is also used in solid-state devices, as stabilizer of fuel cells which operate at high temperature.

Terbium in the environment

Terbium is one of the rarer rare-earth elements, although is twice as common in the Earth's crust as silver. It is never found in nature as free element, but is is contained in many minerals. The most important ore are monazite, bastnasite and cerite. The main mining areas are China, USA, India, Sri Lanka, Brazil and Australia and reserves fo terbium are estimated to be around 300.000 tonnes. World production is 10 tonnes a year.

Health effects of terbium

Terbium has no bilogical role, it may be mildly toxic by ingestion. Terbium powder and compound are very irritating if they come into contact with the skin and the eyes. Its toxicity has not been investigated in detail.

Environmental effects of terbium

Terbium poses no environmental threat to plants or animals.

Sources of periodic table.

Back to the periodic table of elements.

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