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Praseodym (Pr)
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Praseodym 59Pr140.907
1885 von Baron Auer von Welsbach in Wien, Österreich, dargestellt.
[Griechisch, prasios didymos = grüner Zwilling]
French: praséodyme
English: praseodymium
Italian: praseodimio
Spanish: praseodimio
Beschreibung: Weiches, verformbares, silberfarbiges Metall der Lanthanoid-Gruppe. Reagiert langsam mit Sauerstoff, schnell mit Wasser. Verwendung: Legierungen für Permanentmagnete, Feuersteine, gelbes Glas zum Augenschutz beim Schweißen usw.
Further Materials properties
| Crystal structure: |
(cell dimensions/pm), space group, |
|---|---|
| X-ray diffractions mass absorption coefficients: | CuKa 363 (µ/r) / cm2g-1 MoKa 50.7 (µ/r) / cm2g-1 |
| Neutron scattering length: | 0.445 b/10-12 cm |
| Thermal neutron capture cross-section: | 11.5 sa / barns |
| Density: | 6773 kg/m-3 [293 K] |
| Melting point: | 930.85°C / 1204°K |
| Boiling point: | 3511.85°C / 3785°K |
| Molar volume: | 20.80 cm3 |
| Thermal conductivity: | 12.5 [300 K] W m-1K-1 |
| Coefficient of linear thermal expansion: | 6.79 x 10-6 K-1 |
| Electrical resistivity: | 68 x 10-8 [298 K] Ωm |
| Mass magnetic susceptibility: | +4.47 x 10-7(s) kg-1m3 |
| Radi: | 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 |
| Isotope 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: | Praeseodymium is mildly toxic by ingestion, and is a skin and eye irritant. |
| Level in humans | n.a. but very low |
| Daily dietary intake: | n.a. |
| Total mass of element in average [70 kg] person: |
n.a. but very low |
Geological data
| Minerals: | ||||
|---|---|---|---|---|
| Mineral | Formula | Density | Hardness | Crystal apperance |
| Bastnäsite* | (La,Ce,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 ores: | monazite, bastnäsite |
|---|---|
| World production: | 2400 tonnes/year |
| Producing areas: | USA, Brazil, India, Sri Lanka, Australia |
| Reserves: | c. 2 x 106 tonnes |
| Specimen: | available as chips, foil and ingots. Safe. Pr powder is a skin and eye irritant. Care! |
| Abundances | |
|---|---|
| Sun: | 4.6 (relative to H = 1 x 1012) |
| Earth's crust: | 9.5 ppm |
| Seawater | |
| Atlantic surface: | 4 x 10-7 ppm |
| Atlantic deep: | 7 x 10-7 ppm |
| Pacific surface: | 4.4 x 10-7 ppm |
| Pacific deep: | 10 x 10-7 ppm |
| Residence time: | n.a. |
| Oxidation state: | III |
Source: Emsley, J. (1998) The Elements (3rd Edition)
Other sizes and specifications on request
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