| Atomic Mass | 145 |
|---|---|
| Electron Configuration | [Xe]6s24f5 |
| Oxidation States | +3 |
| Year Discovered | 1945 |
| Atomic Mass | 145 |
|---|---|
| Electron Configuration | [Xe]6s24f5 |
| Oxidation States | +3 |
| Year Discovered | 1945 |
| Element Name | Promethium |
|---|---|
| Element Symbol | Pm |
| InChI | InChI=1S/Pm |
| InChIKey | VQMWBBYLQSCNPO-UHFFFAOYSA-N |
| Atomic Weight |
145 145 [145] |
|---|---|
| Electron Configuration |
[Xe]6s24f5 |
| Atomic Radius |
Van der Waals Atomic Radius : 236 pm (Van der Waals) Empirical Atomic Radius : 185pm (Empirical) Covalent Atomic Radius : 199 pm (Covalent) |
| Oxidation States |
+3 3, 2 (a mildly basic oxide) |
| Ground Level |
6H°5/2 |
| Ionization Energy |
5.55 eV 5.58187 ± 0.00004 eV |
| Atomic Spectra |
Lines Holdings Levels Holdings |
| Physical Description |
Solid |
| Element Classification |
Metal |
| Element Period Number |
6 |
| Element Group Number |
- Lanthanide |
| Density |
7.26 grams per cubic centimeter |
| Melting Point |
1315 K (1042°C or 1908°F) 1042°C |
| Boiling Point |
3273 K (3000°C or 5432°F) 3000°C |
| Estimated Crustal Abundance |
Not Applicable |
| Estimated Oceanic Abundance |
Not Applicable |
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.
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.
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.
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.
See more information at the Promethium compound page.
| CID | Name | Formula | SMILES | Molecular Weight |
|---|---|---|---|---|
| 23944 | promethium | Pm | [Pm] | 144.91276 |
| 104906 | promethium-147 | Pm | [147Pm] | 146.91514 |
| 161149 | promethium-149 | Pm | [149Pm] | 148.91834 |
| 167342 | promethium-145 | Pm | [145Pm] | 144.91276 |
| 177521 | promethium-141 | Pm | [141Pm] | 140.9136 |
| 177645 | promethium-150 | Pm | [150Pm] | 149.9210 |
| 167138 | promethium-148 | Pm | [148Pm] | 147.91748 |
| 167177 | promethium-143 | Pm | [143Pm] | 142.91094 |
| 177486 | promethium-146 | Pm | [146Pm] | 145.91470 |
| 177485 | promethium-144 | Pm | [144Pm] | 143.91260 |
| 177678 | promethium-151 | Pm | [151Pm] | 150.92122 |
| 10130012 | promethium-142 | Pm | [142Pm] | 141.9129 |
| 16048796 | promethium-153 | Pm | [153Pm] | 152.92416 |
| Stable Isotope Count | 0 |
|---|
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], [433], [434].
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].
![Fig. IUPAC.61.1: The beta-ray backscatter technique requires a layer of ¹⁴⁷Pm between the cladding and the graphite layer to measure the thickness of the graphite along the inner surface of the cladding tube. (Modified from [308]).](https://pubchem.ncbi.nlm.nih.gov/images/iupac/j_pac-2015-0703_fig_085.jpg)
| Isotope | Atomic Mass (uncertainty) [u] | Abundance (uncertainty) |
|---|---|---|
| 145Pm | 144.9127559(33) | |
| 147Pm | 146.9151450(19) |
| Nuclide | Atomic Mass and Uncertainty [u] | Half Life and Uncertainty | Discovery Year | Decay Modes, Intensities and Uncertainties [%] |
|---|---|---|---|---|
| 126Pm | 125.957327 ± 0.000537 [Estimated] | 500 ms [Estimated] | β+ ?; β+p ? | |
| 127Pm | 126.951358 ± 0.000429 [Estimated] | 1 s [Estimated] | β+ ?; p ? | |
| 128Pm | 127.948234 ± 0.000322 [Estimated] | 1.0 s ± 0.3 | 1999 | β+≈100%; β+p= ?; p=0% |
| 129Pm | 128.942909 ± 0.000322 [Estimated] | 2.4 s ± 0.9 | 2004 | β+=100%; β+p ?; p ? |
| 130Pm | 129.940451 ± 0.000215 [Estimated] | 2.6 s ± 0.2 | 1985 | β+=100%; β+p=? |
| 131Pm | 130.935834 ± 0.000215 [Estimated] | 6.3 s ± 0.8 | 1998 | β+=100% |
| 132Pm | 131.933840 ± 0.00016 [Estimated] | 6.2 s ± 0.6 | 1977 | β+=100%; β+p≈5e-5% |
| 133Pm | 132.929782000 ± 0.000054 | 13.5 s ± 2.1 | 1977 | β+=100% |
| 133Pmm | 132.929782000 ± 0.000054 | 8 s [Estimated] | 1996 | β+ ?; IT ? |
| 134Pm | 133.928326000 ± 0.000045 | 22 s ± 1 | 1977 | β+=100% |
| 134Pmm | 133.928326000 ± 0.000045 | ~5 s | 1988 | β+=100% |
| 134Pmn | 133.928326000 ± 0.000045 | 20 us ± 1 | 2009 | IT=100% |
| 135Pm | 134.924785000 ± 0.000089 | 49 s ± 3 | 1975 | β+=100% |
| 135Pmm | 134.924785000 ± 0.000089 | 40 s ± 3 | 1989 | β+=100% |
| 136Pm | 135.923595949 ± 0.000074152 | 107 s ± 6 | 1988 | β+=100% |
| 136Pmm | 135.923595949 ± 0.000074152 | 90 s ± 35 | 1982 | β+=100% |
| 136Pmn | 135.923595949 ± 0.000074152 | 1.5 us ± 0.1 | 1987 | IT=100% |
| 137Pm | 136.920479519 ± 0.000014 | 2 m [Estimated] | 1975 | β+ ? |
| 137Pmm | 136.920479519 ± 0.000014 | 2.4 m ± 0.1 | 1973 | β+=100% |
| 138Pm | 137.919576119 ± 0.000012456 | 3.24 m ± 0.05 | 1973 | β+=100% |
| 138Pmm | 137.919576119 ± 0.000012456 | 10 s ± 2 | β+=100% | |
| 139Pm | 138.916799228 ± 0.000014587 | 4.15 m ± 0.05 | 1967 | β+=100% |
| 139Pmm | 138.916799228 ± 0.000014587 | 180 ms ± 20 | 1975 | IT≈100%; β+ ? |
| 140Pm | 139.916035918 ± 0.000026001 | 9.2 s ± 0.2 | 1966 | β+=100% |
| 140Pmm | 139.916035918 ± 0.000026001 | 5.95 m ± 0.05 | 1966 | β+=100% |
| 141Pm | 140.913555081 ± 0.000015 | 20.90 m ± 0.05 | 1952 | β+=100% |
| 141Pmm | 140.913555081 ± 0.000015 | 630 ns ± 20 | 1970 | IT=100% |
| 141Pmn | 140.913555081 ± 0.000015 | >2 us | 1985 | IT=100% |
| 142Pm | 141.912890982 ± 0.00002533 | 40.5 s ± 0.5 | 1959 | β+=100%; e+=77.1±2.7%; ε=22.9±2.7% |
| 142Pmm | 141.912890982 ± 0.00002533 | 2.0 ms ± 0.2 | 1971 | IT=100% |
| 142Pmn | 141.912890982 ± 0.00002533 | 67 us ± 5 | 1974 | IT=100% |
| 143Pm | 142.910938068 ± 0.00000316 | 265 d ± 7 | 1952 | ε=100%; e+<5.7e-6% |
| 144Pm | 143.912596208 ± 0.000003126 | 363 d ± 14 | 1952 | ε=100%; e+<8e-5% |
| 144Pmm | 143.912596208 ± 0.000003126 | 780 ns ± 200 | 1993 | IT=100% |
| 144Pmn | 143.912596208 ± 0.000003126 | ~2.7 us | 1994 | IT=100% |
| 145Pm | 144.912755748 ± 0.000003011 | 17.7 y ± 0.4 | 1951 | ε=100%; α=2.8e-7% |
| 146Pm | 145.914702240 ± 0.000004589 | 5.53 y ± 0.05 | 1960 | ε=66.0±1.3%; β-=34.0±1.3% |
| 147Pm | 146.915144944 ± 0.000001382 | 2.6234 y ± 0.0002 | 1947 | β-=100% |
| 148Pm | 147.917481091 ± 0.000006108 | 5.368 d ± 0.007 | 1947 | β-=100% |
| 148Pmm | 147.917481091 ± 0.000006108 | 41.29 d ± 0.11 | 1951 | β-=95.8±0.6%; IT=4.2±0.6% |
| 149Pm | 148.918341507 ± 0.000002344 | 53.08 h ± 0.05 | 1947 | β-=100% |
| 149Pmm | 148.918341507 ± 0.000002344 | 35 us ± 3 | 1966 | IT=100% |
| 150Pm | 149.920990014 ± 0.000021504 | 2.698 h ± 0.015 | 1952 | β-=100% |
| 151Pm | 150.921216613 ± 0.000004949 | 28.40 h ± 0.04 | 1952 | β-=100% |
| 152Pm | 151.923505185 ± 0.000027809 | 4.12 m ± 0.08 | 1958 | β-=100% |
| 152Pmm | 151.923505185 ± 0.000027809 | 7.52 m ± 0.08 | 1971 | β-=100% |
| 152Pmn | 151.923505185 ± 0.000027809 | 13.8 m ± 0.2 | 1971 | β-=100%; IT ? |
| 153Pm | 152.924156252 ± 0.000009729 | 5.25 m ± 0.02 | 1962 | β-=100% |
| 154Pm | 153.926712791 ± 0.000026861 | 2.68 m ± 0.07 | 1958 | β-=100% |
| 154Pmm | 153.926712791 ± 0.000026861 | 1.73 m ± 0.10 | 1958 | β-=100% |
| 155Pm | 154.928136951 ± 0.000005065 | 41.5 s ± 0.2 | 1982 | β-=100% |
| 156Pm | 155.931114059 ± 0.000001275 | 27.4 s ± 0.5 | 1986 | β-=100% |
| 156Pmm | 155.931114059 ± 0.000001275 | 2.3 s ± 2.0 | 2007 | IT≈98%; β-≈2% |
| 157Pm | 156.933121298 ± 0.000007521 | 10.56 s ± 0.10 | 1987 | β-=100% |
| 158Pm | 157.936546948 ± 0.000000953 | 4.8 s ± 0.5 | 1987 | β-=100% |
| 158Pmm | 157.936546948 ± 0.000000953 | >16 us | 2015 | IT=?; β- ? |
| 159Pm | 158.939286409 ± 0.000010777 | 1.49 s ± 0.13 | 1998 | β-=100% |
| 159Pmm | 158.939286409 ± 0.000010777 | 4.42 us ± 0.17 | 2015 | IT=100% |
| 160Pm | 159.943215272 ± 0.0000022 | 725 ms ± 57 | 2012 | β-=100%; β-n ? |
| 160Pmm | 159.943215272 ± 0.0000022 | >700 ms | 2020 | β- ?; IT ?; β-n ? |
| 161Pm | 160.946229837 ± 0.0000097 | 1.05 s ± 0.15 | 2012 | β-=100%; β-n ? |
| 161Pmm | 160.946229837 ± 0.0000097 | 0.89 us ± 0.09 | 2015 | IT=100% |
| 162Pm | 161.950574 ± 0.000322 [Estimated] | 630 ms ± 180 | 2012 | β-=100%; β-n ? |
| 163Pm | 162.953881 ± 0.000429 [Estimated] | 255 ms ± 25 | 2012 | β-=100%; β-n ? |
| 164Pm | 163.958819 ± 0.000429 [Estimated] | 300 ms >550ns [Estimated] | 2018 | β- ?; β-n ? |
| 165Pm | 164.962780 ± 0.000537 [Estimated] | 260 ms >550ns [Estimated] | 2018 | β- ?; β-n ? |
