AskDefine | Define praseodymium

Dictionary Definition

praseodymium n : a soft yellowish-white trivalent metallic element of the rare earth group; can be recovered from bastnasite or monazite by an ion-exchange process [syn: Pr, atomic number 59]

User Contributed Dictionary

English

Noun

  1. A metallic chemical element (symbol Pr) with an atomic number of 59.

Translations

External links

For etymology and more information refer to: http://elements.vanderkrogt.net/elem/pr.html (A lot of the translations were taken from that site with permission from the author)

Extensive Definition

For other meanings of the abbreviation Pr, see PR.
Praseodymium ( or /ˌpreɪsioʊˈdɪmiəm/) is a chemical element that has the symbol Pr and atomic number 59.

Notable characteristics

Praseodymium is a soft silvery metal in the lanthanide group. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that spalls off when exposed to air, exposing more metal to oxidation. For this reason, praseodymium should be stored under a light mineral oil or sealed in glass.

Applications

Uses of praseodymium:

History

The name praseodymium comes from the Greek prasios, meaning green, and didymos, twin. Praseodymium is frequently misspelled as praseodynium.
In 1841, Mosander extracted the rare earth didymium from lanthana. In 1874, Per Teodor Cleve concluded that didymium was in fact two elements, and in 1879, Lecoq de Boisbaudran isolated a new earth, samarium, from didymium obtained from the mineral samarskite. In 1885, the Austrian chemist baron Carl Auer von Welsbach separated didymium into two elements, praseodymium and neodymium, which gave salts of different colors.
Leo Moser (not to be confused with Leo Moser, a mathematician) investigated the use of praseodymium in glass coloration in the late 1920s. The result was a yellow-green glass given the name "Prasemit". However, a similar color could be achieved with colorants costing only a minute fraction of what praseodymium cost in the late 1920s, such that the color was not popular, few pieces were made, and examples are now extremely rare. Moser also blended praseodymium with neodymium to produce "Heliolite" glass ("Heliolit" in German), which was more widely accepted. The first enduring commercial use of praseodymium, which continues today, is in the form of a yellow-orange stain for ceramics, "Praseodymium Yellow", which is a solid-solution of praseodymium in the zirconium silicate (zircon) lattice. This stain has no hint of green in it. By contrast, at sufficiently high loadings, praseodymium glass is distinctly green, rather than pure yellow.
Praseodymium has historically been a rare earth whose supply has exceeded demand. Unwanted as such, much praseodymium has been marketed as a mixture with lanthanum and cerium, or "LCP" for the first letters of each of the constituents, for use in replacing the traditional lanthanide mixtures that were inexpensively made from monazite or bastnaesite. LCP is what remains of such mixtures, after the desirable neodymium, and all the heavier, rarer and more valuable lanthanides have been removed, by solvent extraction. However, as technology progresses, praseodymium has been found possible to incorporate into neodymium-iron-boron magnets, thereby extending the supply of the much in demand neodymium. So LC is starting to replace LCP as a result.

Occurrence

Praseodymium is available in small quantities in Earth’s crust (9.5 ppm). It is found in the rare earth minerals monazite and bastnasite, typically comprising about 5% of the lanthanides contained therein, and can be recovered from bastnasite or monazite by an ion exchange process, or by counter-current solvent extraction.
Praseodymium also makes up about 5% of misch metal.

Compounds

Praseodymium compounds include:

Isotopes

Naturally occurring praseodymium is composed of one stable isotope, 141Pr. Thirty-eight radioisotopes have been characterized with the most stable being 143Pr with a half-life of 13.57 days and 142Pr with a half-life of 19.12 hours. All of the remaining radioactive isotopes have half-lives that are less than 5.985 hours and the majority of these have half-lives that are less than 33 seconds. This element also has six meta states with the most stable being 138mPr (t½ 2.12 hours), 142mPr (t½ 14.6 minutes) and 134mPr (t½ 11 minutes).
The isotopes of praseodymium range in atomic weight from 120.955 u (121Pr) to 158.955 u (159Pr). The primary decay mode before the stable isotope, 141Pr, is electron capture and the primary mode after is beta minus decay. The primary decay products before 141Pr are element 58 (cerium) isotopes and the primary products after are element 60 (neodymium) isotopes.

Precautions

Like all rare earths, praseodymium is of low to moderate toxicity. Praseodymium has no known biological role.

References

External links

praseodymium in Arabic: براسيوديميوم
praseodymium in Bengali: প্রাসিওডিমিয়াম
praseodymium in Belarusian: Празеадым
praseodymium in Bosnian: Prazeodijum
praseodymium in Catalan: Praseodimi
praseodymium in Czech: Praseodym
praseodymium in Corsican: Praseodimiu
praseodymium in Danish: Praseodym
praseodymium in German: Praseodym
praseodymium in Estonian: Praseodüüm
praseodymium in Modern Greek (1453-): Πρασινοδύμιο
praseodymium in Spanish: Praseodimio
praseodymium in Esperanto: Prazeodimo
praseodymium in Basque: Praseodimio
praseodymium in Persian: پراسیودیمیوم
praseodymium in French: Praséodyme
praseodymium in Friulian: Praseodimi
praseodymium in Manx: Prashodymmium
praseodymium in Galician: Praseodimio
praseodymium in Korean: 프라세오디뮴
praseodymium in Armenian: Պրազեդիում
praseodymium in Croatian: Praseodimij
praseodymium in Ido: Prazeodimio
praseodymium in Indonesian: Praseodimium
praseodymium in Italian: Praseodimio
praseodymium in Hebrew: פרסאודימיום
praseodymium in Latin: Praseodymium
praseodymium in Latvian: Prazeodīms
praseodymium in Luxembourgish: Praseodym
praseodymium in Lithuanian: Prazeodimis
praseodymium in Lojban: jinmrprase,odimi
praseodymium in Hungarian: Prazeodímium
praseodymium in Malayalam: പ്രസിയോഡൈമിയം
praseodymium in Dutch: Praseodymium
praseodymium in Japanese: プラセオジム
praseodymium in Javanese: Praseodimium
praseodymium in Norwegian: Praseodym
praseodymium in Norwegian Nynorsk: Praseodym
praseodymium in Polish: Prazeodym
praseodymium in Portuguese: Praseodímio
praseodymium in Russian: Празеодим
praseodymium in Sicilian: Praseodimiu
praseodymium in Slovak: Prazeodým
praseodymium in Slovenian: Prazeodim
praseodymium in Serbian: Празеодијум
praseodymium in Serbo-Croatian: Prazeodijum
praseodymium in Finnish: Praseodyymi
praseodymium in Swedish: Praseodym
praseodymium in Tamil: பிரசியோடைமியம்
praseodymium in Thai: เพรซีโอดิเมียม
praseodymium in Ukrainian: Празеодим
praseodymium in Chinese: 镨
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