Author: Jan Scholten
2.0 Lanthanides physical
The Lanthanides are soft, silver white metals. They are chemically very much alike, which makes them difficult to separate form each other.
Lanthanides have very strong magnetic qualities, much stronger than iron. The strong magnets in tiny electric motors are only possible with Lanthanides, so they abound everywhere in our high tech culture.
Lanthanides have strong light effects. They are very refractory and thus used in light equipment and lenses. They have special qualities that make them suitable for lasers. They are used in CD's, where light detects the pattern oh holes in the CD. The colors of the salts are used as colorants. The emissions of the Lanthanide compound are used in color television.
The Lanthanides are members of the group "rare earth" metals, together with Scandium and Yttrium. Although called "rare", they are quite common. Cerium is more common than Copper and even the least common Lanthanide, Thulium, is more common than Silver. Promethium is the only one that doesn't exist on earth, as it decays radioactivity.
Discovery: from 1887 till the last in 1947, Promethium.
Name: Comes form the first Lanthanide, Lanthanum.
The name means hidden.
They are also called Lanthanoids.
Biology: No known functions; stimulate metabolism.
Ores: Gadolinit: (Ce, La, Nd, Y)2FeBe2Si2O10.
Xenotime, Monazite: LnPO4.
Melting points: 700-1000 degrees,
Boiling points: 1500-3000 degrees.
The first group is also called Cerit earths: Ce, Pr, Nd, Pm, Sm, Eu.
The second, heavier group are called Ytterearths: Gd, Tb, Dy, Ho, Er, Tm.
A prominent feature is the lanthanoid contraction: the radius of the lanthanoid ions (the 3 valence) decreases from Lanthanum to Lutetium.
1. Magnets: electromagnetism, strong magnets, electric motors, speakers.
2. Optical devices: lenses, color television, compact discs, refraction; rare earth oxides Pr2O3 are the most refractory substances.
4. Light: color television, colorants.
5. Electron microscope.