Praseodymium (Pr)
lanthanideSolid
Masse atomique relative standard
140,90766 uConfiguration électronique
[Xe] 6s2 4f3Point de fusion
930,85 °CPoint d’ébullition
3519,85 °CMasse volumique
6770 kg/m³États d’oxydation
0, +1, +2, +3, +4, +5Électronégativité (Pauling)
1,13Énergie d’ionisation (1re)
5,4702 eVAnnée de découverte
1885Rayon atomique
185 pmDétails
Praseodymium is a light lanthanide and one of the rare-earth elements. In nature it occurs with other lanthanides, chiefly in minerals such as monazite and bastnäsite, and only in the +3 oxidation state under normal geochemical conditions. Its chemistry is dominated by Pr³⁺ salts and oxides, but the element is more readily oxidized to Pr⁴⁺ than most neighboring lanthanides. Praseodymium is technologically important in permanent magnets, optical materials, ceramics, and specialized alloys.
Praseodymium is soft, silvery, malleable, and ductile. It is somewhat more resistant to corrosion in air than europium, lanthanum, cerium, or neodymium, but it does develop a green oxide coating that falls off when exposed to air. As with other rare-earth metals, it should be kept under a light mineral oil or sealed in plastic.
The name derives from the Greek prasios for "green" and didymos for "twin" because of the pale green salts it forms. Praseodymium was discovered by the Austrian chemist Carl Auer (Baron von Welsbach) in 1885, who separated it and the element neodymium from a didymium sample (didymium had previously been thought to be a separate element).
Praseodymium was discovered by Carl F. Auer von Welsbach, an Austrian chemist, in 1885. He separated praseodymium, as well as the element neodymium, from a material known as didymium. Today, praseodymium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements.
From the Greek word prasios, green, and didymos, twin. In 1841 Mosander extracted the rare earth didymia from lanthana; in 1879, Lecoq de Boisbaudran isolated a new earth, samaria, from didymia obtained from the mineral samarskite. Six years later, in 1885, von Welsbach separated didymia into two others, praseodymia and neodymia, which gave salts of different colors. As with other rare earths, compounds of these elements in solution have distinctive sharp spectral absorption bands or lines, some of which are only a few Angstroms wide.
Pure praseodymium is a soft, silvery metal with a pale yellow cast when freshly cut. It tarnishes readily in air, forming oxide layers that can spall, so metal is usually stored under mineral oil, inert gas, or vacuum. It is malleable and reacts slowly with water, faster with dilute acids.
The largest use of praseodymium is in neodymium-iron-boron magnet alloys, where it can partly replace neodymium and help adjust magnetic and processing properties. Praseodymium compounds color glasses and ceramic glazes yellow to green, and mixed praseodymium-neodymium glass is used in didymium filters for glassworking eye protection. Praseodymium is also used in some mischmetal alloys, polishing and catalytic materials, and doped optical crystals or fibers for specialized lasers and signal devices.
Praseodymium's primary use is as an alloying agent with magnesium to create high-strength metals that are used in aircraft engines. Praseodymium also makes up about 5% of Misch metal, a material that is used to make flints for lighters. Praseodymium forms the core of carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Praseodymium is added to fiber optic cables as a doping agent where it is used as a signal amplifier. Praseodymium salts are used to give glasses and enamels a yellow color. Praseodymium is also a component of didymium glass, which is used to make certain types of welder's and glass blower's goggles.
Misch metal, used in making cigarette lighters, contains about 5% praseodymium metal. The rare-earth oxides, including Pr2O3 are among the most refractory substances known. Along with other rare earths, it is widely used as a core material for carbon arcs used by the motion picture industry for studio lighting and projection. Salts of praseodymium are used to color glasses and enamels; when mixed with certain other materials, praseodymium produces an intense and unusually clean yellow color in glass. Didymium glass, of which praseodymium is a component, is a colorant for welders goggles.
Isotopes in Medicine
Because of its relatively short half-life (19.12 h) and decay primarily by beta decay (96.3 percent beta decay and 3.7 percent alpha decay), 142Pr has been proposed for two main innovative applications in medicine, namely in microsphere brachytherapy and in eye plaque brachytherapy [425] M. C. Ferreira. Dosimetric Study of Beta-Minus Emitter Praseodymium-142: Applications in Microsphere Brachytherapy for Hepatocellular Carcinoma and Brachytherapy for Ocular Squamous Cell Carcinoma, East Carolina University Greenville, North Carolina, USA (2013).. 142Pr is advantageous because penetration of the beta fraction of the radiation is limited to a few millimeters in tissue, therefore limiting the dose of radiation to the treated site. 142Pr may be produced either by fast neutron activation or thermal neutron activation of stable 141Pr.
Research in metal-bearing radiopharmaceuticals is being conducted to determine the most efficient way to produce and process radioactive metals for in vivo tracing. This research has led to the development of a potential radionuclide generator that administers radioactive metal complexes to be observed during positron emission tomography (PET) imaging. A n(140Nd)/n(140Pr) amount-ratio radionuclide generator has been designed to administer 140Pr complexes, such as 140Pr-DTPA, to be used as a tracer during a PET scan [426] K. P. Zhernosekov. Radiochemical Aspects of Production and Processing of Radiometals for Preparation of Metalloradiopharmaceuticals, Johannes Gutenberg-Universität Mainz: Department of Chemistry, Pharmacy and Earth Sciences (2017), Feb. 27; https://publications.ub.uni-mainz.de/theses/volltexte/2006/1043/pdf/1043.pdf.. The half-life of 140Pr is 3.4 min. The n(140Nd)/n(140Pr) ratio radionuclide generators can also be used for administering 140Pr-phosphonate complexes to identify the development of skeletal metastases. Once the skeletal metastases are found, 153Sm-EDTMP can be administered as a radiotherapeutic agent to treat bone cancer (Fig. IUPAC.59.1) [426] K. P. Zhernosekov. Radiochemical Aspects of Production and Processing of Radiometals for Preparation of Metalloradiopharmaceuticals, Johannes Gutenberg-Universität Mainz: Department of Chemistry, Pharmacy and Earth Sciences (2017), Feb. 27; https://publications.ub.uni-mainz.de/theses/volltexte/2006/1043/pdf/1043.pdf.. The half-life of 153Sm is 1.9 days.
Praseodymium forms mainly trivalent compounds containing Pr³⁺, including praseodymium(III) chloride, PrCl₃, praseodymium(III) fluoride, PrF₃, and praseodymium(III) oxide, Pr₂O₃. Mixed-valence and tetravalent oxide chemistry is important: praseodymium(IV) oxide, PrO₂, and the nonstoichiometric oxide often written Pr₆O₁₁ are useful oxidizing and ceramic materials. Praseodymium salts are commonly green, and their optical absorption bands are sharp because 4f electrons are partly shielded from the ligand environment.
See more information at the Praseodymium compound page.
Praseodymium metal dust and filings can burn, and freshly divided material should be treated as a fire risk. Soluble praseodymium salts have low to moderate acute toxicity compared with many heavy metals, but they are not nutrients and should not be inhaled or ingested. Industrial hazards mainly involve dust exposure, reactive metal handling, hot processing, and co-exposure to acids, fluorides, or other chemicals used in separation and alloy production.
Praseodymium is dispersed in the crust with other light rare-earth elements and is concentrated by geological processes in phosphate and carbonate minerals. It is generally immobile in neutral soils and waters because Pr³⁺ strongly adsorbs to clays, oxides, and organic matter or precipitates with phosphate and carbonate. Mining and processing can release rare-earth-bearing dusts and tailings, but praseodymium is not known to have a specific biological role.
Praseodymium is produced as part of rare-earth mining and separation rather than from ores mined solely for Pr. Bastnäsite, monazite, and related concentrates are chemically cracked, and solvent extraction or ion-exchange methods separate the closely similar lanthanides. Demand is strongly linked to high-performance permanent magnets, where praseodymium and neodymium are often managed together as a didymium-rich stream. Supply is constrained by rare-earth separation capacity, environmental controls, and the need to balance production of many co-occurring lanthanides. Recycling from magnets and manufacturing scrap is technically possible and increasingly important, but separation from complex products remains difficult.
The element occurs along with other rare-earth elements in a variety of minerals. Monazite and bastnasite are the two principal commercial sources of the rare-earth metals. It was prepared in relatively pure form in 1931.
Praseodymium is much less abundant in the cosmos than iron-group elements but is a normal product of neutron-capture nucleosynthesis. Its stable isotope, ¹⁴¹Pr, is formed through s-process and r-process pathways in evolved stars and explosive events. In planetary materials it follows other refractory lithophile rare-earth elements and is enriched in differentiated crustal rocks relative to primitive mantle materials.
- Natural praseodymium is essentially monoisotopic, consisting of stable ¹⁴¹Pr.
- The name comes from Greek words meaning “green twin,” referring to the color of its salts and its separation from didymr
- Pr₆O₁₁ is often called praseodymium oxide, although it is not a simple single-valence oxide.
- Praseodymium can replace part of neodymium in many commercial magnet compositions.
- Pr³⁺ absorption lines can give praseodymium glass a distinctive yellow-green filter behavior.
Images
Propriétés
Propriétés physiques
- Rayon atomique (empirique)
- 185 pm Comparer : Rayon atomique (empirique) de tous les éléments →
- Rayon covalent
- 203 pm Comparer : Rayon covalent de tous les éléments →
- Rayon de van der Waals
- 239 pm Comparer : Rayon de van der Waals de tous les éléments →
- Masse volumique
- 6770 kg/m³ Comparer : Masse volumique de tous les éléments →
- Volume molaire
- 0,0208 L/mol
- Phase aux CNTP
- Solide Comparer : Phase aux CNTP de tous les éléments →
- Point de fusion
- 930,85 °C Comparer : Point de fusion de tous les éléments →
- Point d’ébullition
- 3519,85 °C Comparer : Point d’ébullition de tous les éléments →
- Conductivité thermique
- 12,5 W/(m·K) Comparer : Conductivité thermique de tous les éléments →
- Capacité thermique massique
- 0,193 J/(g·K) Comparer : Capacité thermique massique de tous les éléments →
- Capacité thermique molaire
- 27,2 J/(mol·K) Comparer : Capacité thermique molaire de tous les éléments →
- Structure cristalline
- Hexagonal compact Comparer : Structure cristalline de tous les éléments →
Propriétés chimiques
- Électronégativité (Pauling)
- 1,13 Comparer : Électronégativité (Pauling) de tous les éléments →
- Affinité électronique
- 0,962 eV
- Énergie d’ionisation (1re)
- 5,4702 eV Comparer : Énergie d’ionisation (1re) de tous les éléments →
- Énergie d’ionisation (2e)
- 10,631037 eV Comparer : Énergie d’ionisation (2e) de tous les éléments →
- Énergie d’ionisation (3e)
- 21,623774 eV Comparer : Énergie d’ionisation (3e) de tous les éléments →
- Énergie d’ionisation (4e)
- 38,981134 eV Comparer : Énergie d’ionisation (4e) de tous les éléments →
- Énergie d’ionisation (5e)
- 57,530198 eV Comparer : Énergie d’ionisation (5e) de tous les éléments →
- États d’oxydation
- 0, +1, +2, +3, +4, +5 Comparer : États d’oxydation de tous les éléments →
- Électrons de valence
- 3 Comparer : Électrons de valence de tous les éléments →
- Configuration électronique
- [Xe] 6s2 4f3
Propriétés thermodynamiques
- Enthalpie de fusion
- 0,07141006 eV Comparer : Enthalpie de fusion de tous les éléments →
- Enthalpie de vaporisation
- 3,078199 eV Comparer : Enthalpie de vaporisation de tous les éléments →
- Enthalpie de sublimation
- 3,430585 eV
- Enthalpie d’atomisation
- 3,430585 eV
- Enthalpie d’atomisation
- 3,699021 eV
Propriétés nucléaires
- Protons
- 59 Comparer : Protons de tous les éléments →
- Neutrons
- 82 Comparer : Neutrons de tous les éléments →
- Isotopes connus
- 41 Comparer : Isotopes connus de tous les éléments →
- Isotopes stables
- 1 Comparer : Isotopes stables de tous les éléments →
- Isotope le plus stable
- Pr-141
- Année de découverte
- 1885
Abondance
- Abondance (croûte terrestre)
- 9,2 mg/kg Comparer : Abondance (croûte terrestre) de tous les éléments →
- Abondance (océan)
- 6,4 × 10−7 mg/L Comparer : Abondance (océan) de tous les éléments →
Structure cristalline
- Paramètre de maille a
- 367 pm
Structure électronique
- Électrons par couche
- 2, 8, 18, 21, 8, 2 Comparer : Électrons par couche de tous les éléments →
Identifiants
- Numéro CAS
- 7440-10-0 Comparer : Numéro CAS de tous les éléments →
- Symbole de terme
- 4I°9/2
- InChI
- InChI=1S/Pr
- Clé InChI
- PUDIUYLPXJFUGB-UHFFFAOYSA-N
Configuration électronique Mesuré
Pr: 4f³ 6s²[Xe] 4f³ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f³ 6s²Modèle atomique
Les isotopes diffèrent par leur nombre de neutrons, leur masse et leur stabilité — pas par la configuration électronique de l’atome neutre.
Modèle atomique schématique, non à l’échelle.
Empreinte atomique
Spectre d’émission / d’absorption
Distribution isotopique
| Nombre de masse | Masse atomique (u) | Abondance naturelle | Demi-vie |
|---|---|---|---|
| 141 Stable | 140,9076576 ± 0,0000023 | 100,0000% | Stable |
Phase / État
Explication: 905,9 °C en dessous du point de fusion (930,85 °C)
Schématique, non à l’échelle
Points de transition de phase
Énergies de transition
Énergie nécessaire pour faire fondre 1 mol au point de fusion
Énergie nécessaire pour vaporiser 1 mol au point d’ébullition
Énergie nécessaire pour sublimer 1 mol au point de sublimation
Masse volumique
Dans les conditions standard
Dans les conditions standard
Spectres atomiques
Affichage de 10 sur 59. Tri par charge ionique croissante.
Raies répertoriées ?
| Ion | Charge | Nombre total de raies | Probabilités de transition | Désignations des niveaux |
|---|---|---|---|---|
| Pr I | 0 | 182 | 0 | 0 |
| Pr II | +1 | 548 | 172 | 356 |
| Pr III | +2 | 372 | 0 | 0 |
| Pr IV | +3 | 135 | 0 | 0 |
| Pr V | +4 | 12 | 0 | 0 |
Niveaux répertoriés ?
| Ion | Charge | Niveaux |
|---|---|---|
| Pr I | 0 | 430 |
| Pr II | +1 | 201 |
| Pr III | +2 | 430 |
| Pr IV | +3 | 104 |
| Pr V | +4 | 9 |
| Pr VI | +5 | 2 |
| Pr VII | +6 | 2 |
| Pr VIII | +7 | 2 |
| Pr IX | +8 | 2 |
| Pr X | +9 | 2 |
Rayons ioniques
| Charge | Coordinence | Spin | Rayon |
|---|---|---|---|
| +3 | 6 | N/D | 99 pm |
| +3 | 8 | N/D | 112.6 pm |
| +3 | 9 | N/D | 117.9 pm |
| +4 | 6 | N/D | 85 pm |
| +4 | 8 | N/D | 96 pm |
Composés
Isotopes (1)
| Nombre de masse | Masse atomique (u) | Abondance naturelle | Demi-vie | Mode de désintégration | |
|---|---|---|---|---|---|
| 141 Stable | 140,9076576 ± 0,0000023 | 100,0000% | Stable | stable |
Propriétés étendues
Rayons covalents (données étendues)
- Rayon covalent (Pyykkö)
- 176 pm
- Rayon covalent (Pyykkö, liaison double)
- 138 pm
- Rayon covalent (Pyykkö, liaison triple)
- 128 pm
Rayons de van der Waals
- Alvarez
- 292 pm
- UFF
- 360,6 pm
- MM3
- 273 pm
Rayons atomiques et métalliques
- Rayon atomique (Rahm)
- 286 pm
Échelles de numérotation
- Mendeleev
- 17
- Pettifor
- 31
- Glawe
- 30
Échelles d’électronégativité
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 4
Polarisabilité et dispersion
- Polarisabilité dipolaire
- 216 a.u.
- Polarisabilité dipolaire (incertitude)
- 20 a.u.
- C₆ (Gould–Bučko)
- 3760 Ha·Bohr6
Paramètres de Miedema
- Volume molaire de Miedema
- 20,79 cm3/mol
- Densité électronique de Miedema
- 2
Risque d’approvisionnement et économie
- Concentration de la production
- 97
- Risque relatif d’approvisionnement
- 10
- Répartition des réserves
- 50
- Stabilité politique (principal producteur)
- 24
- Stabilité politique (principal détenteur de réserves)
- 24
Transitions de phase et allotropes
| Point de fusion | 1204,15 K |
| Point d’ébullition | 3793,15 K |
Catégories d’états d’oxydation
Données de référence avancées
Constantes d’écran (13)
| n | Orbitale | σ |
|---|---|---|
| 1 | s | 1,1694 |
| 2 | p | 4,2306 |
| 2 | s | 15,538 |
| 3 | d | 13,8476 |
| 3 | p | 19,1756 |
| 3 | s | 19,499 |
| 4 | d | 32,7028 |
| 4 | f | 37,8992 |
| 4 | p | 29,9432 |
| 4 | s | 28,6668 |
Détail des rayons cristallins (5)
| Charge | CN | Spin | rcrystal (pm) | Origine |
|---|---|---|---|---|
| 3 | VI | 113 | from r^3 vs V plots, | |
| 3 | VIII | 126,6 | from r^3 vs V plots, | |
| 3 | IX | 131,9 | from r^3 vs V plots, | |
| 4 | VI | 99 | from r^3 vs V plots, | |
| 4 | VIII | 110 | from r^3 vs V plots, |
Modes de désintégration des isotopes (58)
| Isotope | Mode | Intensité |
|---|---|---|
| 121 | p | 100% |
| 122 | B+ | — |
| 122 | B+p | — |
| 123 | B+ | — |
| 123 | B+p | — |
| 124 | B+ | 100% |
| 124 | B+p | — |
| 125 | B+ | 100% |
| 125 | B+p | — |
| 126 | B+ | 100% |
Facteurs de diffusion des rayons X (508)
| Énergie (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 1,26325 |
| 10,1617 | — | 1,25455 |
| 10,3261 | — | 1,24591 |
| 10,4931 | — | 1,23732 |
| 10,6628 | — | 1,22879 |
| 10,8353 | — | 1,22033 |
| 11,0106 | — | 1,21192 |
| 11,1886 | — | 1,20357 |
| 11,3696 | — | 1,19528 |
| 11,5535 | — | 1,18704 |
Données complémentaires
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
9.2 milligrams per kilogram
Références (1)
- [5] Praseodymium https://education.jlab.org/itselemental/ele059.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
6.4×10-7 milligrams per liter
Références (1)
- [5] Praseodymium https://education.jlab.org/itselemental/ele059.html
Sources
Sources of this element.
The element occurs along with other rare-earth elements in a variety of minerals. Monazite and bastnasite are the two principal commercial sources of the rare-earth metals. It was prepared in relatively pure form in 1931.
Références (1)
- [6] Praseodymium https://periodic.lanl.gov/59.shtml
Production
Production of this element (from raw materials or other compounds containing the element).
Ion-exchange and solvent extraction techniques have led to much easier isolation of the rare earths and the cost has dropped greatly in the past few years. Praseodymium can be prepared by several methods, such as by calcium reduction of the anhydrous chloride of fluoride.
Références (1)
- [6] Praseodymium https://periodic.lanl.gov/59.shtml
Références
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
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The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Praseodymium.
The element property data was retrieved from publications.