Praseodymium (Pr)
lanthanideSolid
Peso atómico estándar
140,90766 uConfiguración electrónica
[Xe] 6s2 4f3Punto de fusión
930,85 °CPunto de ebullición
3519,85 °CDensidad
6770 kg/m³Estados de oxidación
0, +1, +2, +3, +4, +5Electronegatividad (Pauling)
1,13Energía de ionización (1.ª)
5,4702 eVAño de descubrimiento
1885Radio atómico
185 pmDetalles
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.
Imágenes
Propiedades
Físicas
- Radio atómico (empírico)
- 185 pm Comparar Radio atómico (empírico) de todos los elementos →
- Radio covalente
- 203 pm Comparar Radio covalente de todos los elementos →
- Radio de van der Waals
- 239 pm Comparar Radio de van der Waals de todos los elementos →
- Densidad
- 6770 kg/m³ Comparar Densidad de todos los elementos →
- Volumen molar
- 0,0208 L/mol
- Fase en CNPT
- Sólido Comparar Fase en CNPT de todos los elementos →
- Punto de fusión
- 930,85 °C Comparar Punto de fusión de todos los elementos →
- Punto de ebullición
- 3519,85 °C Comparar Punto de ebullición de todos los elementos →
- Conductividad térmica
- 12,5 W/(m·K) Comparar Conductividad térmica de todos los elementos →
- Capacidad calorífica específica
- 0,193 J/(g·K) Comparar Capacidad calorífica específica de todos los elementos →
- Capacidad calorífica molar
- 27,2 J/(mol·K) Comparar Capacidad calorífica molar de todos los elementos →
- Estructura cristalina
- Hexagonal compacta Comparar Estructura cristalina de todos los elementos →
Químicas
- Electronegatividad (Pauling)
- 1,13 Comparar Electronegatividad (Pauling) de todos los elementos →
- Afinidad electrónica
- 0,962 eV
- Energía de ionización (1.ª)
- 5,4702 eV Comparar Energía de ionización (1.ª) de todos los elementos →
- Energía de ionización (2.ª)
- 10,631037 eV Comparar Energía de ionización (2.ª) de todos los elementos →
- Energía de ionización (3.ª)
- 21,623774 eV Comparar Energía de ionización (3.ª) de todos los elementos →
- Energía de ionización (4.ª)
- 38,981134 eV Comparar Energía de ionización (4.ª) de todos los elementos →
- Energía de ionización (5.ª)
- 57,530198 eV Comparar Energía de ionización (5.ª) de todos los elementos →
- Estados de oxidación
- 0, +1, +2, +3, +4, +5 Comparar Estados de oxidación de todos los elementos →
- Electrones de valencia
- 3 Comparar Electrones de valencia de todos los elementos →
- Configuración electrónica
- [Xe] 6s2 4f3
Termodinámicas
- Calor de fusión
- 0,07141006 eV Comparar Calor de fusión de todos los elementos →
- Calor de vaporización
- 3,078199 eV Comparar Calor de vaporización de todos los elementos →
- Calor de sublimación
- 3,430585 eV
- Calor de atomización
- 3,430585 eV
- Entalpía de atomización
- 3,699021 eV
Nucleares
- Protones
- 59 Comparar Protones de todos los elementos →
- Neutrones
- 82 Comparar Neutrones de todos los elementos →
- Isótopos conocidos
- 41 Comparar Isótopos conocidos de todos los elementos →
- Isótopos estables
- 1 Comparar Isótopos estables de todos los elementos →
- Isótopo más estable
- Pr-141
- Año de descubrimiento
- 1885
Abundancia
- Abundancia (corteza terrestre)
- 9,2 mg/kg Comparar Abundancia (corteza terrestre) de todos los elementos →
- Abundancia (océano)
- 6,4 × 10−7 mg/L Comparar Abundancia (océano) de todos los elementos →
Estructura cristalina
- Constante de red a
- 367 pm
Estructura electrónica
- Electrones por capa
- 2, 8, 18, 21, 8, 2 Comparar Electrones por capa de todos los elementos →
Identificadores
- Número CAS
- 7440-10-0 Comparar Número CAS de todos los elementos →
- Símbolo del término
- 4I°9/2
- InChI
- InChI=1S/Pr
- Clave InChI
- PUDIUYLPXJFUGB-UHFFFAOYSA-N
Configuración electrónica Medido
Pr: 4f³ 6s²[Xe] 4f³ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f³ 6s²Modelo atómico
Los isótopos cambian el número de neutrones, la masa y la estabilidad, pero no la configuración electrónica de un átomo neutro.
Modelo atómico esquemático, no a escala.
Huella atómica
Espectro de emisión / absorción
Distribución isotópica
| Número másico | Masa atómica (u) | Abundancia natural | Periodo de semidesintegración |
|---|---|---|---|
| 141 Estable | 140,9076576 ± 0,0000023 | 100,0000% | Estable |
Fase / Estado
Motivo: 905,9 °C por debajo del punto de fusión (930,85 °C)
Esquemático, no a escala
Puntos de transición de fase
Energías de transición
Energía necesaria para fundir 1 mol en el punto de fusión
Energía necesaria para vaporizar 1 mol en el punto de ebullición
Energía necesaria para sublimar 1 mol en el punto de sublimación
Densidad
En condiciones estándar
En condiciones estándar
Espectros atómicos
Se muestran 10 de 59. Ordenado por carga del ion (ascendente).
Líneas disponibles ?
| Ion | Carga | Total de líneas | Probabilidades de transición | Designaciones de los niveles |
|---|---|---|---|---|
| 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 |
Niveles disponibles ?
| Ion | Carga | Niveles |
|---|---|---|
| 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 |
Radios iónicos
| Carga | Coordinación | Espín | Radio |
|---|---|---|---|
| +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 |
Compuestos
Isótopos (1)
| Número másico | Masa atómica (u) | Abundancia natural | Periodo de semidesintegración | Modo de desintegración | |
|---|---|---|---|---|---|
| 141 Estable | 140,9076576 ± 0,0000023 | 100,0000% | Estable | stable |
Propiedades ampliadas
Radios covalentes (ampliados)
- Radio covalente (Pyykkö)
- 176 pm
- Radio covalente (Pyykkö, enlace doble)
- 138 pm
- Radio covalente (Pyykkö, enlace triple)
- 128 pm
Radios de van der Waals
- Alvarez
- 292 pm
- UFF
- 360,6 pm
- MM3
- 273 pm
Radios atómicos y metálicos
- Radio atómico (Rahm)
- 286 pm
Escalas de numeración
- Mendeleev
- 17
- Pettifor
- 31
- Glawe
- 30
Escalas de electronegatividad
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 4
- Robles–Bartolotti
- 4
Polarizabilidad y dispersión
- Polarizabilidad dipolar
- 216 a.u.
- Polarizabilidad dipolar (incert.)
- 20 a.u.
- C₆ (Gould–Bučko)
- 3760 Ha·Bohr6
Parámetros de Miedema
- Volumen molar de Miedema
- 20,79 cm3/mol
- Densidad electrónica de Miedema
- 2
Riesgo de suministro y economía
- Concentración de la producción
- 97
- Riesgo relativo de suministro
- 10
- Distribución de las reservas
- 50
- Estabilidad política (principal productor)
- 24
- Estabilidad política (país con mayores reservas)
- 24
Transiciones de fase y alótropos
| Punto de fusión | 1204,15 K |
| Punto de ebullición | 3793,15 K |
Categorías de estados de oxidación
Datos de referencia avanzados
Constantes de apantallamiento (13)
| n | Orbital | 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 |
Detalle de los radios cristalinos (5)
| Carga | CN | Espín | rcrystal (pm) | Origen |
|---|---|---|---|---|
| 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, |
Modos de desintegración de los isótopos (58)
| Isótopo | Modo | Intensidad |
|---|---|---|
| 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% |
Factores de dispersión de rayos X (508)
| Energía (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 |
Datos adicionales
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
9.2 milligrams per kilogram
Referencias (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
Referencias (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.
Referencias (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.
Referencias (1)
- [6] Praseodymium https://periodic.lanl.gov/59.shtml
Referencias
(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.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
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.