I am writing about an element known as lanthanum. The name comes from the greek
word lanthano, meaning to be hidden or concealed. It was discovered by the Swedish
chemist Carl Mosander in 1839. It has the atomic weight of 138.91 and the atomic
number of 57. It is found with other rare earth's in monazite, bastnasite, and other
minerals. Monazite and bastnasite are principle ores in which lanthanum occurs in
percentages up to 25 and 38 percent. Misch metal, is used in making litter flints, which
contains about 25 percent lanthanum. It is always found among the fission products of
uranium, thorium, and plutonium. It is separated from the other rare earth's by fractional
crystallization. Lanthanum melts at about 920 degrees and boils at about 3469 degrees.
Lanthanum is used in misch metal to make important metal alloys. For example the oxide
Lanthanum was isolated in relatively pure form in 1923. Ion-exchange and
solvent extraction techniques have led to mush easier isolation of the so called"rare earth"
elements. In recent years lanthanum and other rare earth metals have become much more
abundant. Lanthanum can be produced by reducing the anhydrous fluoride with calcium.
Lanthanum is one of the earth's most reactive rare earth metals. Lanthanum is silvery
white in color and ductile. It is malleable enough to be cut with a knife.When lanthanum
is exposed to air it can oxidizes. Cold water will attack lanthanum more slowly, and hot
water attacks it much more rapidly.
Lanthanum reacts with carbon, nitrogen, boron, selenium, silicon, phosphorus,
sulfur, and with halogens. At 310 degrees celcius, lanthanum changes from a hexagonal
to a face centered cubic structure, and at 865 degrees celius it again transforms into a
body centered cubic structure. Natural lanthanum is a mixture of two isotopes. One is
stable and one of which is radioactive with a ver...