Praseodymium was discovered in 1885 by Carl Auer von Welsbach. It is named after the Greek words "prasios didymos" meaning "green twin". Praseodymium is a soft, silvery metal that is used in alloys, permanent magnets, and to colour glasses and ceramics yellow. It has low toxicity to humans.

1. The symbol is one
commonly used for the
astrological birth sign of
Gemini (‘the twins’). The
green colour, together with
this symbol, reflects the
origin of the element’s
name, from the Greek
‘prasinos’, meaning ‘green’,
and ‘didymos’, meaning
‘twin’.

2.  Praseodymium was discovered by Carl F. Auer
von Welsbach at 1885 in Austria.
 It came from the Greek words "prasios didymos"
meaning "green twin"
 In 1885, Carl Auer von Welsbach separated an
"earth" called didymia obtained from the
mineral samarskite into two earths,
praseodymia and neodymia, which gave salts
of different colours. The separation required
the repeated fractionation of ammonium
didymium nitrate.

3.  Praseodymium is used in a variety of alloys. The high-
strength alloy it forms with magnesium is used in
aircraft engines. Mischmetal is an alloy containing about
5% praseodymium and is used to make flints for
cigarette lighters. It is also used in alloys for permanent
magnets.
 Along with other lanthanide elements, it is used in
carbon arc electrodes for studio lighting and projection.
 Praseodymium salts are used to colour glasses, enamel
and glazes an intense and unusually clean yellow.
Praseodymium oxide is a component of didymium glass
(along with neodymium). This glass is used in goggles
used by welders and glassmakers, because it filters out
the yellow A soft, silvery metallight and infrared (heat)
radiation.

4.  Praseodymium is a soft, malleable, ductile metal
with a yellowish, metallic shine.
 Malleable means capable of being hammered
into a thin sheet. Ductile means capable of being
made into thin wires. Praseodymium has a
melting point of 930°C (1,710°F) and a boiling
point of about 3,200°C (about 5,800°F).
 Its density is 6.78 to 6.81 grams per cubic
centimeter. Two allotropes of praseodymium
exist. Allotropes are forms of an element with
different physical and chemical properties. One
allotrope, the "alpha" form, changes into a second
allotrope, the "beta" form, at about 800°C.

5.  When it becomes moist, praseodymium reacts with
oxygen in air to form praseodymium oxide.
 Praseodymium oxide (Pr2O3) forms as a greenish-
yellow scale (like rust) on the surface of the metal.
 To protect praseodymium for this reaction, it is
stored under mineral oil or covered with a plastic
wrap.
 Like many other metals, praseodymium also reacts
with water and with acids. In these reactions,
hydrogen gas is released.

6.  Praseodymium has no known biological role. It
has low toxicity.
 Praseodymium occurs along with other
lanthanide elements in a variety of minerals.
The two principal sources are monazite and
bastnaesite. It is extracted from these minerals
by ion exchange and solvent extraction.
 Praseodymium metal is prepared by reducing
anhydrous chloride with calcium.

7. Atomic radius, non-bonded
(Å)
2.40
Covalent radius
(Å)
1.90
Electron affinity (kJ mol−1) 92.819
Electronegativity
(Pauling scale)
1.13
Ionisation energies
(kJ mol−1)
1st
528.064
2nd
1017.92
3rd
2086.399
4th
3761
5th
5550.8
6th
-
7th
-
8th
-

8. Relative supply risk 9.5
Crustal abundance (ppm) 0.3
Relative supply risk 9.5
Recycling rate (%) <10
SubstitutabilityHigh
Production concentration (%) 97
Reserve distribution (%) 50

9. Top 3 producers
1) China
2) Russia
3) Malaysia
Top 3 reserve holders
1) China
2) CIS Countries (inc. Russia)
3) USA
Political stability of top producer 24.1
Political stability of top reserve holder 24.1

10.  Anti-inflammatory effects of chloride salts of
praseodymium, gadolinium and ytterbium were
investigated, using various experimental
inflammatory models in rats.
 The lanthanide salts administered by oral route
showed no significant effect, but when injected
intraperitoneally they significantly inhibited the
carrageenin-induced oedema, proportional to their
doses ranging from 15 to 75 mg/kg.
 They also reduced nystatin- induced oedema and
vascular permeability response to histamine and
serotonin.

11.  Pronounced inhibitory effect of lanthanide salts
at the dose of 50 mg/kg, i.p., was observed in
histamine- and serotonin-induced changes
invascular permeability.
 Repeated administration of lanthanide salts in
the dose of 20 mg/kg for 13 d significantly
inhibited arthritis development.
 The same dose of these salts for a 6-d period
similarly reduced granuloma formation.
However, praseodymium, gadolinium and
ytterbium chlorides showed no significant
difference among themselves and their anti-
infammatory effects were samller than those
from phenylbutaz