Promethium (Pm)
lanthanideSolid
標準原子量
[145]電子配置
[Xe] 6s2 4f5融点
1041.85 °C沸点
2999.85 °C密度
7260 kg/m³酸化数
+2, +3電気陰性度（Pauling）
データなし第1イオン化エネルギー
5.58187 eV発見年
1902原子半径
185 pm詳細
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.
画像
性質
物理的性質
- 原子半径（経験値）
- 185 pm 全元素の原子半径（経験値）を比較 →
- 共有結合半径
- 199 pm 全元素の共有結合半径を比較 →
- ファンデルワールス半径
- 236 pm 全元素のファンデルワールス半径を比較 →
- 密度
- 7260 kg/m³ 全元素の密度を比較 →
- 標準温度・圧力（STP）での相
- 固体 全元素の標準温度・圧力（STP）での相を比較 →
- 融点
- 1041.85 °C 全元素の融点を比較 →
- 沸点
- 2999.85 °C 全元素の沸点を比較 →
- 熱伝導率
- 17.9 W/(m·K) 全元素の熱伝導率を比較 →
化学的性質
- 電子親和力
- 0.129 eV
- 第1イオン化エネルギー
- 5.58187 eV 全元素の第1イオン化エネルギーを比較 →
- 第2イオン化エネルギー
- 10.938038 eV 全元素の第2イオン化エネルギーを比較 →
- 第3イオン化エネルギー
- 22.440077 eV 全元素の第3イオン化エネルギーを比較 →
- 第4イオン化エネルギー
- 41.170142 eV 全元素の第4イオン化エネルギーを比較 →
- 第5イオン化エネルギー
- 61.700212 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- +2, +3 全元素の酸化数を比較 →
- 価電子
- 3 全元素の価電子を比較 →
- 電子配置
- [Xe] 6s2 4f5
熱力学的性質
- 融解熱
- 0.07980515 eV 全元素の融解熱を比較 →
- 蒸発熱
- 3.005649 eV 全元素の蒸発熱を比較 →
- 昇華熱
- 3.161113 eV
- 原子化熱
- 3.161113 eV
原子核
- 陽子数
- 61 全元素の陽子数を比較 →
- 中性子数
- 84 全元素の中性子数を比較 →
- 既知の同位体
- 40 全元素の既知の同位体を比較 →
- 安定同位体
- 0 全元素の安定同位体を比較 →
- 質量数（最も安定な同位体）
- 145
- 最も安定な同位体
- Pm-145
- 発見年
- 1902
存在度
データなし
結晶構造
データなし
電子構造
- 各電子殻の電子数
- 2, 8, 18, 23, 8, 2 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 7440-12-2 全元素のCAS登録番号を比較 →
- 項記号
- 6H°5/2
- InChI
- InChI=1S/Pm
- InChI Key
- VQMWBBYLQSCNPO-UHFFFAOYSA-N
電子配置 測定値
Pm: 4f⁵ 6s²[Xe] 4f⁵ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁵ 6s²原子モデル
同位体によって中性子数、質量、安定性は変わりますが、中性原子の電子配置は変わりません。
模式的な原子モデルです。実際の縮尺とは異なります。
原子の指紋
発光／吸収スペクトル
同位体分布
安定同位体はありません。
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 |
|---|---|---|---|
| 160 放射性 | 159.9431 ± 0.00032 | データなし | 725 ms |
| 162 放射性 | 161.95022 ± 0.00043 | データなし | 630 ms |
| 126 放射性 | 125.95792 ± 0.00054 | データなし | 500 ms |
| 144 放射性 | 143.9125964 ± 0.0000034 | データなし | 363 日 |
| 164 放射性 | 163.958819 ± 0.000429 | データなし | 300 ms |
相／状態
理由: 融点（1041.85 °C）より1016.9 °C低い
模式図、実際の縮尺とは異なります
相転移点
相転移エネルギー
融点で1 molを融解させるのに必要なエネルギー
沸点で1 molを蒸発させるのに必要なエネルギー
昇華点で1 molを昇華させるのに必要なエネルギー
密度
標準条件下
標準条件下
原子スペクトル
全61件中10件を表示しています。 イオンの電荷の昇順で並べています。
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| 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 |
結晶構造のデータはありません
イオン半径
| 電荷 | 配位 | スピン | 半径 |
|---|---|---|---|
| +3 | 6 | データなし | 97 pm |
| +3 | 8 | データなし | 109.3 pm |
| +3 | 9 | データなし | 114.39999999999999 pm |
化合物
同位体 (5)
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 160 放射性 | 159.9431 ± 0.00032 | データなし | 725 ms | β- =100%β-n ? | |
| 162 放射性 | 161.95022 ± 0.00043 | データなし | 630 ms | β- =100%β-n ? | |
| 126 放射性 | 125.95792 ± 0.00054 | データなし | 500 ms | β+ ?β+p ? | |
| 144 放射性 | 143.9125964 ± 0.0000034 | データなし | 363 日 | ε =100%e+<8e-5% | |
| 164 放射性 | 163.958819 ± 0.000429 | データなし | 300 ms | β- ?β-n ? |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 173 pm
- 共有結合半径（Pyykkö、二重結合）
- 135 pm
ファンデルワールス半径
- UFF
- 354.7 pm
- MM3
- 272 pm
原子半径と金属半径
- 原子半径（Rahm）
- 283 pm
番号付けの尺度
- Mendeleev
- 21
- Pettifor
- 29
- Glawe
- 28
電気陰性度の尺度
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
分極率と分散
- 双極子分極率
- 200 a.u.
- 双極子分極率（不確かさ）
- 20 a.u.
- C₆ (Gould–Bučko)
- 3340 Ha·Bohr6
ミーデマパラメータ
- ミーデマモル体積
- 20.25 cm3/mol
- ミーデマ電子密度
- 2
相転移と同素体
| 融点 | 1315.15 K |
酸化数の分類
専門参考データ
遮蔽定数 (13)
| n | 軌道 | 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 |
結晶半径の詳細 (3)
| 電荷 | CN | スピン | rcrystal (pm) | 由来 |
|---|---|---|---|---|
| 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, |
同位体の崩壊形式 (60)
| 同位体 | モード | 強度 |
|---|---|---|
| 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 | — |
X線散乱因子 (508)
| エネルギー (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 |
追加データ
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
Not Applicable
参考文献 (1)
- [5] Promethium https://education.jlab.org/itselemental/ele061.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
Not Applicable
参考文献 (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.
参考文献 (1)
- [6] Promethium https://periodic.lanl.gov/61.shtml
参考文献
(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.