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The Element Terbium

[Click for Isotope Data]





Atomic Number: 65

Atomic Weight: 158.92535

Melting Point: 1629 K (1356°C or 2473°F)

Boiling Point: 3503 K (3230°C or 5846°F)

Density: 8.23 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 6    Group Number: none    Group Name: Lanthanide

What's in a name? Named for the village of Ytterby, Sweden.

Say what? Terbium is pronounced as TUR-beeem.

History and Uses:

The mineral gadolinite ((Ce, La, Nd, Y)2FeBe2Si2O10), discovered in a quarry near the town of Ytterby, Sweden, has been the source of a great number of rare earth elements. In 1843, Carl Gustaf Mosander, a Swedish chemist, was able to separate gadolinite into three materials, which he named yttria, erbia and terbia. As might be expected considering the similarities between their names and properties, scientists soon confused erbia and terbia and, by 1877, had reversed their names. What Mosander called erbia is now called terbia and visa versa. From these two substances, Mosander discovered two new elements, terbium and erbium. Today, terbium can be obtained from the minerals xenotime (YPO4) and euxenite ((Y, Ca, Er, La, Ce, U, Th)(Nb, Ta, Ti)2O6), but is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that typically contains as much as 0.03% terbium.

Terbium is used to dope some types of solid-state devices and, along with zirconium dioxide (ZrO2), as a crystal stabilizer in fuel cells that operate at high temperatures.

Terbia, the renamed material that Mosander discovered in 1843, is terbium oxide (Tb2O3), one of terbium's compounds. Terbia can potentially be used as an activator for green phosphors in television tubes. Sodium terbium borate, another terbium compound, is used to make laser light.

Estimated Crustal Abundance: 1.2 milligrams per kilogram

Estimated Oceanic Abundance: 1.4×10-7 milligrams per liter

Number of Stable Isotopes: 1   (View all isotope data)

Ionization Energy: 5.864 eV

Oxidation States: +3

Electron Shell Configuration:


2s2   2p6

3s2   3p6   3d10

4s2   4p6   4d10   4f9

5s2   5p6