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Praseodymium (Pr)
We are a leading manufacturer and supplier of research materials
Praseodymium 59Pr140.907
Separated in 1885 by Baron Auer von Welsbach at Vienna, Austria.
[Greek, prasios didymos = green twin]
French: praséodyme
German: Praseodym
Italian: praseodimio
Spanish: praseodimio
Description: Preseodymium 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. Praeseodymium is used in alloys for permanent magnets and flints. It is used to make the yellow glass for eye protection for welders, etc.
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)
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