Promethium (Pm)
lanthanideSolid
Masse atomique relative standard
[145]Configuration électronique
[Xe] 6s2 4f5Point de fusion
1041,85 °CPoint d’ébullition
2999,85 °CMasse volumique
7260 kg/m³États d’oxydation
+2, +3Électronégativité (Pauling)
N/DÉnergie d’ionisation (1re)
5,58187 eVAnnée de découverte
1902Rayon atomique
185 pmDétails
Promethium is a radioactive lanthanide and the only rare-earth element with no stable isotope. It behaves chemically like a typical trivalent lanthanide, forming Pm³⁺ compounds that resemble those of neodymium and samarium. Natural promethium exists only in minute, transient amounts from uranium fission and rare decay processes. Usable quantities have been obtained mainly from nuclear-reactor fission products or by neutron irradiation of neodymium.
It is a soft beta emitter; although no gamma rays are emitted, X-radiation can be generated when beta particles impinge on elements of a high atomic number, and great care must be taken in handling it. Promethium salts luminesce in the dark with a pale blue or greenish glow, due to their high radioactivity. Ion-exchange methods led to the preparation of about 10 g of promethium from atomic reactor fuel processing wastes in early 1963. Little is yet generally known about the properties of metallic promethium. Two allotropic modifications exist.
The existence of promethium was predicted by Bohuslav Brauner, a Czech chemist, in 1902. Several groups claimed to have produced the element, but they could not confirm their discoveries because of the difficulty of separating promethium from other elements. Proof of the existence of promethium was obtained by Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell in 1944. Too busy with defense related research in World War II, they did not claim their discovery until 1946. They discovered promethium while analyzing the byproducts of uranium fission that were produced in a nuclear reactor located at Clinton Laboratories in Oak Ridge, Tennessee. Today, Clinton Laboratories is known as Oak Ridge National Laboratory. Today, promethium is still recovered from the byproducts of uranium fission. It can also be produced by bombarding neodymium-146 with neutrons. Neodymium-146 becomes neodymium-147 when it captures a neutron. Neodymium-147, with a half-life of 11 days, decays into promethium-147 through beta decay. Promethium does not occur naturally on earth, although it has been detected in the spectrum of a star in the constellation Andromeda.
Promethium's most stable isotope, promethium-145, has a half-life of 17.7 years. It decays into neodymium-145 through electron capture.
Named after the Greek Prometheus, who, according to mythology, stole fire from heaven. In 1902 Branner predicted the existence of an element between neodymium and samarium, and this was confirmed by Moseley in 1914. In 1941, workers at Ohio State University irradiated neodymium and praseodymium with neutrons, deuterons, and alpha particles, and produced several new radioactivities, which most likely were those of element 61. Wu and Segre, and Bethe, in 1942, confirmed the formation; however, chemical proof of the production of element 61 was lacking because of the difficulty in separating the rare earths from each other at that time. In 1945, Marinsky, Glendenin, and Coryell made the first chemical identification by use of ion-exchange chromatography. Their work was done by fission of uranium and by neutron bombardment of neodymium.
Macroscopic promethium metal has been prepared only in small, highly radioactive quantities. It is generally described as a silvery lanthanide metal, but many ordinary bulk properties are poorly characterized because self-irradiation, heat generation, and scarcity limit direct measurements.
Promethium has had limited practical use, almost entirely isotope-specific. ¹⁴⁷Pm, a beta emitter, was formerly used in luminous paint and small nuclear batteries where its radiation could be absorbed and converted to electrical power. It has also served in thickness gauges and calibration sources. These applications have largely been replaced or restricted because safer, cheaper, or more durable alternatives are available. Today promethium is used mainly for research, source preparation, and specialized radiochemical studies.
Promethium could be used to make a nuclear powered battery. This type of battery would use the beta particles emitted by the decay of promethium to make a phosphor give off light. This light would then be converted into electricity by a device similar to a solar cell. It is expected that this type of battery could provide power for five years.
Promethium could also be used as a portable X-ray source, in radioisotope thermoelectric generators to provide electricity for space probes and satellites, as a source of radioactivity for gauges that measure thickness and to make lasers that can be used to communicate with submerged submarines.
The element has applications as a beta source for thickness gages, and it can be absorbed by a phosphor to produce light. Light produced in this manner can be used for signs or signals that require dependable operation; it can be used as a nuclear-powered battery by capturing light in photocells which convert it into electric current. Such a battery, using 147Pm, would have a useful life of about 5 years. Promethium shows promise as a portable X-ray source, and it may become useful as a heat source to provide auxiliary power for space probes and satellites. More than 30 promethium compounds have been prepared. Most are colored.
Isotopes in Industry
The beta-particle-emitting isotope 147Pm (with a half-life of 2.68 years) is used in the nuclear fuel industry to measure the thickness of the inner surface layer of graphite in the cladding tube where the nuclear fuel rod is placed in a nuclear fuel reactor (Fig. IUPAC.61.1). The graphite serves as a protective layer against mechanical contact between the nuclear fuel rod and the Zircaloy cladding (fuel-rod holding tube) and as a diffusion barrier against fission products. By placing a layer of 147Pm along the inner surface of the cladding before the graphite, the long half-life of 147Pm and constant beta-particle emission provide a reliable and simple technique to measure the thickness of the graphite along the inner surface of the tube (called the beta-ray backscatter technique) [432] J. K. Shultis, R. E. Faw. Fundamentals of Nuclear Science and Engineering, Marcel Dekker, Inc., New York (2002)., [433] M. Kumar, J. Udhayakumar, J. Nuwad, R. Shukla, C. G. S. Pillai, A. Dash, M. Venkatesh. Appl. Radiat. Isot.69, 580 (2011)., [434] R. P. Taleyarkhan. Atoms for Peace: an International Journal.2, 381 (2009)..
The beta decay property of 147Pm makes this radioisotope an ideal candidate for nuclear batteries (beta voltaics). Long-lived power supplies for remote and sometimes hostile environmental conditions are needed for space and sea missions, and nuclear batteries can uniquely serve this role. A nuclear battery using beta voltaics can have an energy density (quantity of energy per unit mass) near a thousand watt-h per kilogram with 21 percent efficiency, which is much greater than the best chemical batteries [435] G. N. Yakubova. “Nuclear batteries with tritium and promethium-147 radioactive sources”, Ph.D dissertation, Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Illinois, USA (2010). http://hdl.handle.net/2142/16849..
Promethium chemistry is dominated by the +3 oxidation state in aqueous solution and solids. Representative compounds include promethium(III) chloride, PmCl₃, promethium(III) oxide, Pm₂O₃, promethium(III) hydroxide, Pm(OH)₃, and promethium(III) nitrate, Pm(NO₃)₃. The Pm³⁺ ion is usually pink to reddish in solution, and its chemistry parallels neighboring lanthanides with gradual changes in ionic radius. Stable +2 or +4 chemistry is not important under ordinary conditions.
See more information at the Promethium compound page.
All promethium isotopes are radioactive, and hazards depend strongly on isotope, activity, chemical form, and containment. ¹⁴⁷Pm emits beta particles with little penetrating power, but it is hazardous if inhaled, ingested, or held close to tissue; shielding can also generate bremsstrahlung X-rays. Soluble promethium salts would be treated as both radioactive materials and chemically toxic heavy-metal lanthanide compounds. Handling requires radiological controls rather than ordinary laboratory precautions alone.
Promethium has no stable environmental reservoir. Natural atoms are produced in trace amounts by spontaneous fission of uranium and by rare nuclear reactions, then decay away. Anthropogenic promethium can occur in spent nuclear fuel and high-level waste. In the environment, Pm³⁺ would be expected to bind to minerals, oxides, and organic matter much like other trivalent lanthanides, but field behavior is rarely studied because concentrations are extremely low and radiological controls dominate.
Promethium is not traded as a normal commodity metal. Historically, ¹⁴⁷Pm was separated from fission-product mixtures in nuclear fuel processing, where it occurs among many chemically similar lanthanides. Separation requires radiochemical facilities, shielding, isotope control, and repeated ion-exchange or solvent-extraction steps. Small amounts can also be produced by neutron irradiation of enriched neodymium targets. Demand is limited, and substitution by tritium, stable phosphors, conventional electronics, or other radioisotopes has reduced most commercial uses.
Searches for the element on earth have been fruitless, and it now appears that promethium is completely missing from the earth's crust. Promethium, however, has been identified in the spectrum of the star HR465 in Andromeda. This element is being formed recently near the star's surface, for no known isotope of promethium has a half-life longer than 17.7 years. Seventeen isotopes of promethium, with atomic masses from 134 to 155 are now known. Promethium-147, with a half-life of 2.6 years, is the most generally useful. Promethium-145 is the longest lived, and has a specific activity of 940 Ci/g.
Promethium is not a persistent cosmic or planetary element because all of its isotopes are radioactive and geologically short-lived. It can be formed in nucleosynthesis processes that make neutron-rich nuclei and in nuclear fission, but any primordial promethium has long decayed. Its presence in stars is sometimes considered as evidence of recent nucleosynthesis or unusual spectral interpretation, rather than a stable elemental abundance.
- Promethium was identified in fission products before it was isolated in visible quantities.
- Its name refers to Prometheus, reflecting its association with nuclear energy.
- ¹⁴⁷Pm decays to samarium-147 by beta emission.
- Promethium fills the only gap among the naturally ordered lanthanides with no stable isotope.
- Chemical separation of promethium is difficult because adjacent lanthanides have very similar Pm³⁺-like chemistry.
Images
Propriétés
Propriétés physiques
- Rayon atomique (empirique)
- 185 pm Comparer : Rayon atomique (empirique) de tous les éléments →
- Rayon covalent
- 199 pm Comparer : Rayon covalent de tous les éléments →
- Rayon de van der Waals
- 236 pm Comparer : Rayon de van der Waals de tous les éléments →
- Masse volumique
- 7260 kg/m³ Comparer : Masse volumique de tous les éléments →
- Phase aux CNTP
- Solide Comparer : Phase aux CNTP de tous les éléments →
- Point de fusion
- 1041,85 °C Comparer : Point de fusion de tous les éléments →
- Point d’ébullition
- 2999,85 °C Comparer : Point d’ébullition de tous les éléments →
- Conductivité thermique
- 17,9 W/(m·K) Comparer : Conductivité thermique de tous les éléments →
Propriétés chimiques
- Affinité électronique
- 0,129 eV
- Énergie d’ionisation (1re)
- 5,58187 eV Comparer : Énergie d’ionisation (1re) de tous les éléments →
- Énergie d’ionisation (2e)
- 10,938038 eV Comparer : Énergie d’ionisation (2e) de tous les éléments →
- Énergie d’ionisation (3e)
- 22,440077 eV Comparer : Énergie d’ionisation (3e) de tous les éléments →
- Énergie d’ionisation (4e)
- 41,170142 eV Comparer : Énergie d’ionisation (4e) de tous les éléments →
- Énergie d’ionisation (5e)
- 61,700212 eV Comparer : Énergie d’ionisation (5e) de tous les éléments →
- États d’oxydation
- +2, +3 Comparer : États d’oxydation de tous les éléments →
- Électrons de valence
- 3 Comparer : Électrons de valence de tous les éléments →
- Configuration électronique
- [Xe] 6s2 4f5
Propriétés thermodynamiques
- Enthalpie de fusion
- 0,07980515 eV Comparer : Enthalpie de fusion de tous les éléments →
- Enthalpie de vaporisation
- 3,005649 eV Comparer : Enthalpie de vaporisation de tous les éléments →
- Enthalpie de sublimation
- 3,161113 eV
- Enthalpie d’atomisation
- 3,161113 eV
Propriétés nucléaires
- Protons
- 61 Comparer : Protons de tous les éléments →
- Neutrons
- 84 Comparer : Neutrons de tous les éléments →
- Isotopes connus
- 40 Comparer : Isotopes connus de tous les éléments →
- Isotopes stables
- 0 Comparer : Isotopes stables de tous les éléments →
- Nombre de masse (isotope le plus stable)
- 145
- Isotope le plus stable
- Pm-145
- Année de découverte
- 1902
Abondance
N/D
Structure cristalline
N/D
Structure électronique
- Électrons par couche
- 2, 8, 18, 23, 8, 2 Comparer : Électrons par couche de tous les éléments →
Identifiants
- Numéro CAS
- 7440-12-2 Comparer : Numéro CAS de tous les éléments →
- Symbole de terme
- 6H°5/2
- InChI
- InChI=1S/Pm
- Clé InChI
- VQMWBBYLQSCNPO-UHFFFAOYSA-N
Configuration électronique Mesuré
Pm: 4f⁵ 6s²[Xe] 4f⁵ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁵ 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
Aucun isotope stable.
| Nombre de masse | Masse atomique (u) | Abondance naturelle | Demi-vie |
|---|---|---|---|
| 160 Radioactif | 159,9431 ± 0,00032 | N/D | 725 ms |
| 162 Radioactif | 161,95022 ± 0,00043 | N/D | 630 ms |
| 126 Radioactif | 125,95792 ± 0,00054 | N/D | 500 ms |
| 144 Radioactif | 143,9125964 ± 0,0000034 | N/D | 363 jours |
| 164 Radioactif | 163,958819 ± 0,000429 | N/D | 300 ms |
Phase / État
Explication: 1016,9 °C en dessous du point de fusion (1041,85 °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 61. Tri par charge ionique croissante.
Raies répertoriées ?
| Ion | Charge | Nombre total de raies | Probabilités de transition | Désignations des niveaux |
|---|---|---|---|---|
| Pm I | 0 | 229 | 0 | 16 |
| Pm II | +1 | 195 | 0 | 9 |
Niveaux répertoriés ?
| Ion | Charge | Niveaux |
|---|---|---|
| Pm I | 0 | 222 |
| Pm II | +1 | 182 |
| Pm III | +2 | 2 |
| Pm IV | +3 | 12 |
| Pm V | +4 | 2 |
| Pm VI | +5 | 2 |
| Pm VII | +6 | 2 |
| Pm VIII | +7 | 2 |
| Pm IX | +8 | 2 |
| Pm X | +9 | 2 |
Données de structure cristalline indisponibles
Rayons ioniques
| Charge | Coordinence | Spin | Rayon |
|---|---|---|---|
| +3 | 6 | N/D | 97 pm |
| +3 | 8 | N/D | 109.3 pm |
| +3 | 9 | N/D | 114.39999999999999 pm |
Composés
Isotopes (5)
| Nombre de masse | Masse atomique (u) | Abondance naturelle | Demi-vie | Mode de désintégration | |
|---|---|---|---|---|---|
| 160 Radioactif | 159,9431 ± 0,00032 | N/D | 725 ms | β- =100%β-n ? | |
| 162 Radioactif | 161,95022 ± 0,00043 | N/D | 630 ms | β- =100%β-n ? | |
| 126 Radioactif | 125,95792 ± 0,00054 | N/D | 500 ms | β+ ?β+p ? | |
| 144 Radioactif | 143,9125964 ± 0,0000034 | N/D | 363 jours | ε =100%e+<8e-5% | |
| 164 Radioactif | 163,958819 ± 0,000429 | N/D | 300 ms | β- ?β-n ? |
Propriétés étendues
Rayons covalents (données étendues)
- Rayon covalent (Pyykkö)
- 173 pm
- Rayon covalent (Pyykkö, liaison double)
- 135 pm
Rayons de van der Waals
- UFF
- 354,7 pm
- MM3
- 272 pm
Rayons atomiques et métalliques
- Rayon atomique (Rahm)
- 283 pm
Échelles de numérotation
- Mendeleev
- 21
- Pettifor
- 29
- Glawe
- 28
Échelles d’électronégativité
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
Polarisabilité et dispersion
- Polarisabilité dipolaire
- 200 a.u.
- Polarisabilité dipolaire (incertitude)
- 20 a.u.
- C₆ (Gould–Bučko)
- 3340 Ha·Bohr6
Paramètres de Miedema
- Volume molaire de Miedema
- 20,25 cm3/mol
- Densité électronique de Miedema
- 2
Transitions de phase et allotropes
| Point de fusion | 1315,15 K |
Catégories d’états d’oxydation
Données de référence avancées
Constantes d’écran (13)
| n | Orbitale | σ |
|---|---|---|
| 1 | s | 1,2042 |
| 2 | p | 4,2562 |
| 2 | s | 16,0296 |
| 3 | d | 13,9018 |
| 3 | p | 19,4461 |
| 3 | s | 19,8154 |
| 4 | d | 33,26 |
| 4 | f | 37,866 |
| 4 | p | 30,3768 |
| 4 | s | 29,3604 |
Détail des rayons cristallins (3)
| Charge | CN | Spin | rcrystal (pm) | Origine |
|---|---|---|---|---|
| 3 | VI | 111 | from r^3 vs V plots, | |
| 3 | VIII | 123,3 | from r^3 vs V plots, | |
| 3 | IX | 128,4 | from r^3 vs V plots, |
Modes de désintégration des isotopes (60)
| Isotope | Mode | Intensité |
|---|---|---|
| 126 | B+ | — |
| 126 | B+p | — |
| 127 | B+ | — |
| 127 | p | — |
| 128 | B+ | 100% |
| 128 | B+p | — |
| 128 | p | 0% |
| 129 | B+ | 100% |
| 129 | B+p | — |
| 129 | p | — |
Facteurs de diffusion des rayons X (508)
| Énergie (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 0,21641 |
| 10,1617 | — | 0,22429 |
| 10,3261 | — | 0,23246 |
| 10,4931 | — | 0,24092 |
| 10,6628 | — | 0,2497 |
| 10,8353 | — | 0,25879 |
| 11,0106 | — | 0,26822 |
| 11,1886 | — | 0,27798 |
| 11,3696 | — | 0,28811 |
| 11,5535 | — | 0,2986 |
Données complémentaires
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
Références (1)
- [5] Promethium https://education.jlab.org/itselemental/ele061.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
Références (1)
- [5] Promethium https://education.jlab.org/itselemental/ele061.html
Sources
Sources of this element.
Searches for the element on earth have been fruitless, and it now appears that promethium is completely missing from the earth's crust. Promethium, however, has been identified in the spectrum of the star HR465 in Andromeda. This element is being formed recently near the star's surface, for no known isotope of promethium has a half-life longer than 17.7 years. Seventeen isotopes of promethium, with atomic masses from 134 to 155 are now known. Promethium-147, with a half-life of 2.6 years, is the most generally useful. Promethium-145 is the longest lived, and has a specific activity of 940 Ci/g.
Références (1)
- [6] Promethium https://periodic.lanl.gov/61.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.
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 Promethium.
The element property data was retrieved from publications.