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- Name : Lanthanum
- Symbol : La
- Atomic # : 57
- Atom weight: 138.91
- Melting P. : 918
- Boiling P. : 3464
- Oxidation : +3
- Pronounced : LAN-the-nem
- From : Greek lanthanein, "to be hidden"
- Identified : Carl Gustaf Mosander in 1893
- Appearance : Silvery-white, soft, malleable, and ductile metal
- Note : Heads the list of important lanthanide elements
-
- [Properties]
-
- Lanthanum is silvery-white, malleable, and ductile. It is soft enough to
- be cut with a knife. It is a reactive rare earth, second only to europium
- in that respect. It reacts in dry air, burning at about 440 degrees, and
- it reacts vigorously in hot water.
- Lanthanum is in a unique position on the periodic table, at the beginning
- of the lanthanide series. Beginning with lanthanum, itself (element 57),
- the series resumes on a separate line below the main body of the table.
- This line begins with cerium (element 58) and ends with lutetium (element
- 71). Lutetium is not only the last of the lanthanide series, but the last
- of the rare-earth metals as well. The periodic sequence then returns to
- the main body of the table with hafnium (element 72).
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-