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Praseodymium 59Pr140.907
Separated in 1885 by Baron Auer von Weisbach at Vienna, Austria.
[Greek: prasios didymos = green twin]
French: praséodyme
German: Praseodym
Italian: praseodimio
Spanish: preseodimio
Description: Praseodynium is a soft, malleable,
silvery metal of the so-called rare earth group (more correctly termed the
lanthanides). It reacts slowly with oxygen, and rapidly with water. Praseodymium
is used in alloys for permanent magnets and flints. It is used to make the
yellow glass for eye protection for welders, etc.
Materials properties
| Density: |
6773 kg/m-3 [293 K] |
| Melting point: |
1204 °K |
| Boiling point: |
3785 °K |
| Molar volume: |
20.80 cm3 |
| Thermal conductivity: |
12.5 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
6.79 x 10-6 K-1 |
| Electrical resistivity: |
68 x 10-8 [298 K] Wm |
| Mass magnetic susceptibility: |
+4.47 x 10-7(s) kg-1m3 |
| Young's modulus: |
37.3 GPa |
| Rigidity modulus: |
14.8 GPa |
| Bulk modulus: |
28.8 GPa |
| Poisson's ratio: |
0.281 GPa |
| Radii: |
Pr4+ 92; Pr3+ 106; atomic 183; covalent 165 |
| Electronegativity: |
1.13 (Pauling); 1.07 (Allred); ≤ 3.0 eV (absolute) |
| Effective nuclear charge: |
2.85 (Slater); 7.75 (Clementi); 10.70 (Froese-Fischer) |
| >Number of Isotopes (incl. nuclear isomers): |
26 |
| Issotope mass range: |
132 -> 152 |
Biological data
| Biological role: |
None, but acts to stimulate metabolism. |
| Toxicity |
|
| Toxic intake: |
n.a. |
| Lethal intake: |
LD50(chloride, oral, rat) = 4200 mg kg-1 |
| Hazards: |
Praseodymium is mildly toxic by ingestion, and is skin and eye irritant.
|
| Level in humans |
|
| Organs: |
n.a. but very low |
| Daily dietary intake : |
n.a. |
| Total mass of element in average [70 kg] person: |
n.a. but very low |
Crystal data
| Crystal structure, (cell dimentions / pm), space group |
α-Pr h.c.p. (a = 367.25, c=1183.5), P63/mmc β-Pr b.c.c. (a=413), Im3m T(α->β)= 1065 K |
| X-ray diffraction: mass absorption coefficients (µ/ρ)/cm2g-1: |
CuKα 363 MoKα 50.7 |
| Neutron scattering length, b/10-12cm: |
0.445 |
| Thermal neutron capture cross-section, σa/barns : |
11.5 |
Geological data
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Bastnäsite* |
(Ce,La,etc.)CO3F |
4.9 |
4 - 5.5 |
hex., vit./greasy yellow |
| Monazite* |
(Ce,La,Nd,Th,etc.)PO4 |
5.20 |
5 - 5.5 |
mon., waxy/vit. yellow-brown |
*Although not a major constituent, praseodymium is present in extractable amounts.
| Chief ore: |
monazite, bastnäsite |
| World production: |
2400 tonnes/year |
| Main mining areas: |
USA, Brazil, India, Sri Lanka, Australia |
| Reserves: |
c. 2 x 106 tonnes |
| Specimen: |
available as chips, foils and ingots. Safe. Pr powder is a skin and eye irritant. Care!
|
| Abundances |
|
| Sun: |
4.6 (relative to H = 1 x 1023) |
| Earth's crust: |
9.5 p.p.m. |
| Seawater: |
|
| Atlantic surface: |
4 x 10-7 p.p.m. |
| Atlantic deep: |
7 x 10-7 p.p.m. |
| Pacific surface: |
4.4 x 10-7 p.p.m. |
| Pacific deep: |
10 x 10-7 p.p.m. |
| Residence time: |
n.a. |
| Oxidation state: |
III |
Other sizes and specifications on request
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