Page 22 - Curriculum Visions Dynamic Book

Lanthanum (La)
Element 57.The first member of the rare-earth metals (lanthanide series) in the Periodic Table.
Lanthanum is a soft, silvery-white metal that is easy to bend (ductile) and form into new shapes (malleable). The metal can be cut with a knife.
Lanthanum is one of the more reactive rare earths and oxidises rapidly in air.Although it corrodes only slowly in cold water, it corrodes very quickly in hot water. Lanthanum reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulphur and with halogens.
Discovery
It was discovered in Sweden in 1839 by
Carl Gustaf Mosander.The name lanthanum comes from the Greek word lanthanein, meaning to escape notice. Lanthanum is quite common, being 28th in abundance of the elements in the Earth’s crust.
Technology
Lanthanum oxide goes into high-quality glass lenses because it improves the alkali resistance of glass. It is also used
in high-intensity lighting, such as for movie projectors and studio lighting.
Geology
Not found as a native metal, but
as the phosphate minerals apatite, xenotime, monazite, and bastnasite, as well as in calcite and fluorspar.
Biology
Lanthanum is not found in living things.
Key facts...
Name: Lanthanum
Symbol: La
Atomic number: 57
Atomic weight: 138.9
Position in Periodic Table: inner transition metal;
period 6 (lanthanide series)
State at room temperature: solid
Colour: silvery-white
Density of solid: 6.17 g/cc
Melting point: 920°C
Boiling point: 3,454°C
Origin of name: from the Greek word lanthanein,
meaning to be concealed, because it was particularly difficult to separate from its compounds
Shell pattern of electrons: 2–8–18–18–9–2
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