Promethium (Pm)
lanthanideSolid
Peso atomico standard
[145]Configurazione elettronica
[Xe] 6s2 4f5Punto di fusione
1041,85 °CPunto di ebollizione
2999,85 °CDensità
7260 kg/m³Stati di ossidazione
+2, +3Elettronegatività (Pauling)
N/DEnergia di ionizzazione (1ª)
5,58187 eVAnno della scoperta
1902Raggio atomico
185 pmDettagli
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.
Immagini
Proprietà
Fisiche
- Raggio atomico (empirico)
- 185 pm Confronta Raggio atomico (empirico) di tutti gli elementi →
- Raggio covalente
- 199 pm Confronta Raggio covalente di tutti gli elementi →
- Raggio di van der Waals
- 236 pm Confronta Raggio di van der Waals di tutti gli elementi →
- Densità
- 7260 kg/m³ Confronta Densità di tutti gli elementi →
- Fase in condizioni STP
- Solido Confronta Fase in condizioni STP di tutti gli elementi →
- Punto di fusione
- 1041,85 °C Confronta Punto di fusione di tutti gli elementi →
- Punto di ebollizione
- 2999,85 °C Confronta Punto di ebollizione di tutti gli elementi →
- Conducibilità termica
- 17,9 W/(m·K) Confronta Conducibilità termica di tutti gli elementi →
Chimiche
- Affinità elettronica
- 0,129 eV
- Energia di ionizzazione (1ª)
- 5,58187 eV Confronta Energia di ionizzazione (1ª) di tutti gli elementi →
- Energia di ionizzazione (2ª)
- 10,938038 eV Confronta Energia di ionizzazione (2ª) di tutti gli elementi →
- Energia di ionizzazione (3ª)
- 22,440077 eV Confronta Energia di ionizzazione (3ª) di tutti gli elementi →
- Energia di ionizzazione (4ª)
- 41,170142 eV Confronta Energia di ionizzazione (4ª) di tutti gli elementi →
- Energia di ionizzazione (5ª)
- 61,700212 eV Confronta Energia di ionizzazione (5ª) di tutti gli elementi →
- Stati di ossidazione
- +2, +3 Confronta Stati di ossidazione di tutti gli elementi →
- Elettroni di valenza
- 3 Confronta Elettroni di valenza di tutti gli elementi →
- Configurazione elettronica
- [Xe] 6s2 4f5
Termodinamiche
- Calore di fusione
- 0,07980515 eV Confronta Calore di fusione di tutti gli elementi →
- Calore di vaporizzazione
- 3,005649 eV Confronta Calore di vaporizzazione di tutti gli elementi →
- Calore di sublimazione
- 3,161113 eV
- Calore di atomizzazione
- 3,161113 eV
Nucleari
- Protoni
- 61 Confronta Protoni di tutti gli elementi →
- Neutroni
- 84 Confronta Neutroni di tutti gli elementi →
- Isotopi noti
- 40 Confronta Isotopi noti di tutti gli elementi →
- Isotopi stabili
- 0 Confronta Isotopi stabili di tutti gli elementi →
- Numero di massa (isotopo più stabile)
- 145
- Isotopo più stabile
- Pm-145
- Anno della scoperta
- 1902
Abbondanza
N/D
Struttura cristallina
N/D
Struttura elettronica
- Elettroni per guscio
- 2, 8, 18, 23, 8, 2 Confronta Elettroni per guscio di tutti gli elementi →
Identificativi
- Numero CAS
- 7440-12-2 Confronta Numero CAS di tutti gli elementi →
- Simbolo di termine
- 6H°5/2
- InChI
- InChI=1S/Pm
- Chiave InChI
- VQMWBBYLQSCNPO-UHFFFAOYSA-N
Configurazione elettronica Misurato
Pm: 4f⁵ 6s²[Xe] 4f⁵ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁵ 6s²Modello atomico
Gli isotopi modificano il numero di neutroni, la massa e la stabilità — non la configurazione elettronica di un atomo neutro.
Modello atomico schematico, non in scala.
Impronta atomica
Spettro di emissione / assorbimento
Distribuzione isotopica
Nessun isotopo stabile.
| Numero di massa | Massa atomica (u) | Abbondanza naturale | Emivita |
|---|---|---|---|
| 160 Radioattivo | 159,9431 ± 0,00032 | N/D | 725 ms |
| 162 Radioattivo | 161,95022 ± 0,00043 | N/D | 630 ms |
| 126 Radioattivo | 125,95792 ± 0,00054 | N/D | 500 ms |
| 144 Radioattivo | 143,9125964 ± 0,0000034 | N/D | 363 giorni |
| 164 Radioattivo | 163,958819 ± 0,000429 | N/D | 300 ms |
Fase / Stato
Motivo: 1016,9 °C sotto il punto di fusione (1041,85 °C)
Schema non in scala
Punti di transizione di fase
Energie di transizione
Energia necessaria per fondere 1 mol al punto di fusione
Energia necessaria per vaporizzare 1 mol al punto di ebollizione
Energia necessaria per sublimare 1 mol al punto di sublimazione
Densità
In condizioni standard
In condizioni standard
Spettri atomici
Sono visualizzati 10 di 61. Ordinamento per carica ionica crescente.
Righe disponibili ?
| Ione | Carica | Righe totali | Probabilità di transizione | Designazioni dei livelli |
|---|---|---|---|---|
| Pm I | 0 | 229 | 0 | 16 |
| Pm II | +1 | 195 | 0 | 9 |
Livelli disponibili ?
| Ione | Carica | Livelli |
|---|---|---|
| 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 |
Dati sulla struttura cristallina non disponibili
Raggi ionici
| Carica | Coordinazione | Spin | Raggio |
|---|---|---|---|
| +3 | 6 | N/D | 97 pm |
| +3 | 8 | N/D | 109.3 pm |
| +3 | 9 | N/D | 114.39999999999999 pm |
Composti
Isotopi (5)
| Numero di massa | Massa atomica (u) | Abbondanza naturale | Emivita | Modalità di decadimento | |
|---|---|---|---|---|---|
| 160 Radioattivo | 159,9431 ± 0,00032 | N/D | 725 ms | β- =100%β-n ? | |
| 162 Radioattivo | 161,95022 ± 0,00043 | N/D | 630 ms | β- =100%β-n ? | |
| 126 Radioattivo | 125,95792 ± 0,00054 | N/D | 500 ms | β+ ?β+p ? | |
| 144 Radioattivo | 143,9125964 ± 0,0000034 | N/D | 363 giorni | ε =100%e+<8e-5% | |
| 164 Radioattivo | 163,958819 ± 0,000429 | N/D | 300 ms | β- ?β-n ? |
Proprietà estese
Raggi covalenti (dati estesi)
- Raggio covalente (Pyykkö)
- 173 pm
- Raggio covalente (Pyykkö, legame doppio)
- 135 pm
Raggi di van der Waals
- UFF
- 354,7 pm
- MM3
- 272 pm
Raggi atomici e metallici
- Raggio atomico (Rahm)
- 283 pm
Scale di numerazione
- Mendeleev
- 21
- Pettifor
- 29
- Glawe
- 28
Scale di elettronegatività
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
Polarizzabilità e dispersione
- Polarizzabilità dipolare
- 200 a.u.
- Polarizzabilità dipolare (inc.)
- 20 a.u.
- C₆ (Gould–Bučko)
- 3340 Ha·Bohr6
Parametri di Miedema
- Volume molare di Miedema
- 20,25 cm3/mol
- Densità elettronica di Miedema
- 2
Transizioni di fase e allotropi
| Punto di fusione | 1315,15 K |
Categorie degli stati di ossidazione
Dati di riferimento avanzati
Costanti di schermaggio (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 |
Dettaglio dei raggi cristallini (3)
| Carica | 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, |
Modalità di decadimento degli isotopi (60)
| Isotopo | Modalità | Intensità |
|---|---|---|
| 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 | — |
Fattori di diffusione dei raggi X (508)
| Energia (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 |
Dati aggiuntivi
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
Riferimenti (1)
- [5] Promethium https://education.jlab.org/itselemental/ele061.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
Riferimenti (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.
Riferimenti (1)
- [6] Promethium https://periodic.lanl.gov/61.shtml
Riferimenti
(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.