Page 50 - Curriculum Visions Dynamic Book

Erbium (Er)
Element 68.A greyish-silver rare- earth metal (lanthanide) in the Periodic Table. It is soft and can be bent easily. It is reasonably stable in air and oxidises only slowly, unlike many of the rare-earth metals, which tend to tarnish very quickly.
Discovery
Discovered in Sweden in 1843 by Carl Gustaf Mosander, it is one of the three elements separated from the mineral gadolinite, which he called yttria, erbia and terbia. Erbia and terbia got confused, and the names erbia and terbia were switched. In turn, the erbia isolated was actually found to consist of five oxides, now known as erbia, scandia, holmia, thulia and ytterbia. It was only in 1905 that pure erbium oxide was isolated. Erbium metal was only isolated in 1934.
Technology
It is important in fibre-optic telecommunications where it is used in light amplifiers.When erbium is alloyed with vanadium, the vanadium becomes more workable. Pink compounds of
erbium are used to colour glass and enamel.
Geology
It is not found as a native element,
but in gadolinite, xenotime, monazite and bastnasite ores. Erbium oxide is the most common compound. It is a rose-red colour and is soluble in most acids.
Biology
It is not found in living things but is not thought to be harmful.
Key facts...
Name: erbium
Symbol: Er
Atomic number: 68
Atomic weight: 167.26
Position in Periodic Table: inner transition metal;
period 6 (lanthanide series)
State at room temperature: solid
Colour: greyish-silver
Density of solid: 9.07 g/cc
Melting point: 1,529°C
Boiling point: 2,862°C
Origin of name: originally Mosander called it
terbia, but the name was changed to erbium. Shell pattern of electrons: 2–8–18–30–8–2
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