Page 32 - Curriculum Visions Dynamic Book

Terbium (Tb)
Element 65.A silvery-white metal belonging to the rare-earth metals (lanthanides) in the Periodic Table. It is a soft, easily shaped metal and can be cut with a knife. It oxidises slowly in air. It is one of the rarest rare earths.
Discovery
It was discovered in Sweden in 1843 by Carl Gustaf Mosander.
Technology
It is used in the form of sodium terbium borate as a laser material. It also can dope semi-conductors to make electronic components.Terbium oxide makes green phosphors active when applied to the front of colour television tubes. It is likely that it will also find uses in alloys, but techniques for its isolation in significant amounts
have only been developed recently, and so there has not been time for this branch of science to be developed.
Geology
Terbium is not found as a native metal, but in very small amounts in monazite sands combined with other rare earths. Small amounts also occur in cerite, gadolinite, xenotime and euxenite ores. It is about the 58th in abundance in the Earth’s surface rocks.
Biology
Terbium is not found in living things.
Key facts...
Name: terbium
Symbol: Tb
Atomic number: 65
Atomic weight: 158.9
Position in Periodic Table: inner transition
metal; period 6 (lanthanide series) State at room temperature: solid Colour: silvery-white
Density of solid: 8.23 g/cc
Melting point: 1,360°C
Boiling point: 3,041°C
Origin of name: named after Ytterby, a town in
Sweden where there is a famous rare-earth
quarry
Shell pattern of electrons: 2–8–18–27–8–2
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