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REE- Lanthanides

Name

Praseodymium

Symbol

Pr

Atomic number

59

Group

LREE

Subgroup

cerium subgroup

Occurrence / Extraction

It is found in the rare earth minerals monazite and bastnasite. Praseodymium also makes up about 5% of misch metal.

Extraction: obtained metal by reacting praseodymium fluoride (PrF3) by passing an electric current or by making it react with an active metal.

Use


Praseodymium is used in equipment such as colour televisions, fluorescent lamps, energy-saving lamps and glasses.
It is highly valued for ceramics as a bright yellow pigment in praseodymium doped zirconia because of its optimum reflectance at 560 nm.

Much research is being done on its optical properties for use in amplification of telecommunication systems, including as a doping agent in fluoride fibers. Praseodymium forms the core of carbon arc lights which are used in the motion picture industry for studio lighting and projector lights.

It is also used in the scintillator for medical CAT scans.
Praseodymium can be used as alloying agent with magnesium to create high strenght metals that are used in aircraft engines.

Properties

Praseodymium is a soft malleable, silvery-yellow metal.  It reacts slowly with oxygen: when exposed to air it forms a green oxide that does not protect it from further oxidation. It is more resistant to corrosion in air the other rare metals, but it still needs to be stored under oil or coated with plastic. It reacts rapidly with water.

Atomic mass 140.91 g.mol -1
Electronegativity according to Pauling 1.1
Density 6.8 g.cm-3 at 20°C
Melting point 931 °C
Boiling point 3212 °C
 
The origin of the name comes from the Greek words prasios didymos meaning green twin.

Relative abundance

Praseodymium is one of the more common lanthanides. It is thought to occur with an abundance of about 3.5 to 5.5 parts per million in the Earth's crust.

atomic mass (g.mol -1)

140.91

density (g/cm3)

6.8

Oxydation number

+3

Melting point (°C)

931

Boiling point (°C)

3212

Magnetic moment

 

Abundance in the Earth's crust ( ppm)

3.9

discovery

Carl Freiherr Auer von Welsbach  in 1885.