Isotopes of promethium
Encyclopedia
Promethium
(Pm) has no stable isotopes, and does not exist in nature, except in trace quantities as a product of spontaneous fission
. It is a synthetic element, first produced in 1945. Thirty-eight radioisotopes have been characterized, with the most stable being 145Pm with a half-life
of 17.7 years, 146Pm with a half-life of 5.53 years, and 147Pm with a half-life of 2.6234 years. All of the remaining radioactive isotopes have half-lives that are less than 365 days, and the majority of these have half-lives that are less than 30 seconds. This element also has 18 meta states with the most stable being 148mPm (T½ 41.29 days), 152m2Pm (T½ 13.8 minutes) and 152mPm (T½ 7.52 minutes).
The isotopes of promethium range in atomic weight
from 125.95752 u
(126Pm) to 162.95368 u (163Pm). The primary decay mode before the longest-lived isotope, 145Pm, is electron capture
, and the primary mode after is beta minus decay. The primary decay product
s before 145Pm are isotopes of neodymium
and the primary products after are isotopes of samarium
.
Since promethium does not exist as a stable or nearly stable isotope, as you can see under technetium
and all the elements from polonium
to uranium
, a standard atomic mass cannot be given.
. This is a rarely occurring effect of the liquid drop model and stabilities of neighbor element isotopes.
of 2.62 years, and is a fission product
from nuclear reactor
s via beta decay
from neodymium
-147. The isotopes 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, 148Nd, and 150Nd are stable, so the isotopes of promethium with those masses cannot be produced by beta decay
and therefore are not fission products in significant quantities.
149Pm and 151Pm have half-lives of only 53.08 and 28.40 hours, so are not found in spent nuclear fuel
that has been cooled for months or years.
Promethium-147 is used as source for beta radiation and it can be also used for radioisotope thermoelectric generator
s (RTGs) (energy density approximately 2 watts per gram).
Promethium
Promethium is a chemical element with the symbol Pm and atomic number 61. It is notable for being the only exclusively radioactive element besides technetium that is followed by chemical elements with stable isotopes.- Prediction :...
(Pm) has no stable isotopes, and does not exist in nature, except in trace quantities as a product of spontaneous fission
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
. It is a synthetic element, first produced in 1945. Thirty-eight radioisotopes have been characterized, with the most stable being 145Pm with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 17.7 years, 146Pm with a half-life of 5.53 years, and 147Pm with a half-life of 2.6234 years. All of the remaining radioactive isotopes have half-lives that are less than 365 days, and the majority of these have half-lives that are less than 30 seconds. This element also has 18 meta states with the most stable being 148mPm (T½ 41.29 days), 152m2Pm (T½ 13.8 minutes) and 152mPm (T½ 7.52 minutes).
The isotopes of promethium range in atomic weight
Atomic weight
Atomic weight is a dimensionless physical quantity, the ratio of the average mass of atoms of an element to 1/12 of the mass of an atom of carbon-12...
from 125.95752 u
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
(126Pm) to 162.95368 u (163Pm). The primary decay mode before the longest-lived isotope, 145Pm, is electron capture
Electron capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino...
, and the primary mode after is beta minus decay. The primary decay product
Decay product
In nuclear physics, a decay product is the remaining nuclide left over from radioactive decay. Radioactive decay often involves a sequence of steps...
s before 145Pm are isotopes of neodymium
Isotopes of neodymium
Naturally occurring neodymium is composed of 5 stable isotopes, 142Nd, 143Nd, 145Nd, 146Nd and 148Nd, with 142Nd being the most abundant , and 2 radioisotopes, 144Nd and 150Nd...
and the primary products after are isotopes of samarium
Isotopes of samarium
Naturally occurring samarium is composed of five stable isotopes, 144Sm, 149Sm, 150Sm, 152Sm and 154Sm, and two extremely long-lived radioisotopes, 147Sm and 148Sm , with 152Sm being the most abundant...
.
Since promethium does not exist as a stable or nearly stable isotope, as you can see under technetium
Technetium
Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature...
and all the elements from polonium
Polonium
Polonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive element, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Polonium has been studied for...
to uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
, a standard atomic mass cannot be given.
Stability of promethium isotopes
Promethium is one of the two elements with atomic number less than 83 that have only unstable isotopes; the other is technetiumTechnetium
Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature...
. This is a rarely occurring effect of the liquid drop model and stabilities of neighbor element isotopes.
Promethium-147
Promethium-147 has a half-lifeHalf-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 2.62 years, and is a fission product
Fission product
Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The...
from nuclear reactor
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s via beta decay
Beta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
from neodymium
Neodymium
Neodymium is a chemical element with the symbol Nd and atomic number 60. It is a soft silvery metal that tarnishes in air. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach. It is present in significant quantities in the ore minerals monazite and bastnäsite...
-147. The isotopes 142Nd, 143Nd, 144Nd, 145Nd, 146Nd, 148Nd, and 150Nd are stable, so the isotopes of promethium with those masses cannot be produced by beta decay
Beta decay
In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a...
and therefore are not fission products in significant quantities.
149Pm and 151Pm have half-lives of only 53.08 and 28.40 hours, so are not found in spent nuclear fuel
Spent nuclear fuel
Spent nuclear fuel, occasionally called used nuclear fuel, is nuclear fuel that has been irradiated in a nuclear reactor...
that has been cooled for months or years.
Promethium-147 is used as source for beta radiation and it can be also used for radioisotope thermoelectric generator
Radioisotope thermoelectric generator
A radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
s (RTGs) (energy density approximately 2 watts per gram).
Table
| nuclide symbol |
Z(p Proton The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number.... ) |
N(n Neutron The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of... ) |
isotopic mass (u) |
half-life | decay mode(s)Abbreviations: EC: Electron capture Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... IT: Isomeric transition Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
daughter isotope(s)Bold for stable isotopes, bold italics for nearly-stable isotopes (half-life longer than the age of the universe Age of the universe The age of the universe is the time elapsed since the Big Bang posited by the most widely accepted scientific model of cosmology. The best current estimate of the age of the universe is 13.75 ± 0.13 billion years within the Lambda-CDM concordance model... ) |
nuclear spin |
|---|---|---|---|---|---|---|---|
| excitation energy | |||||||
| 126Pm | 61 | 65 | 125.95752(54)# | 0.5# s | |||
| 127Pm | 61 | 66 | 126.95163(64)# | 1# s | 5/2+# | ||
| 128Pm | 61 | 67 | 127.94842(43)# | 1.0(3) s | β+ Beta decay In nuclear physics, beta decay is a type of radioactive decay in which a beta particle is emitted from an atom. There are two types of beta decay: beta minus and beta plus. In the case of beta decay that produces an electron emission, it is referred to as beta minus , while in the case of a... |
128Nd | 6+# |
| p Proton emission Proton emission is a type of radioactive decay in which a proton is ejected from a nucleus. Proton emission can occur from high-lying excited states in a nucleus following a beta decay, in which case the process is known as beta-delayed proton emission, or can occur from the ground state of very... |
127Nd | ||||||
| 129Pm | 61 | 68 | 128.94316(43)# | 3# s [>200 ns] | β+ | 129Nd | 5/2+# |
| 130Pm | 61 | 69 | 129.94045(32)# | 2.6(2) s | β+ | 130Nd | (5+,6+,4+) |
| β+, p (rare) | 129Pr | ||||||
| 131Pm | 61 | 70 | 130.93587(21)# | 6.3(8) s | β+, p | 130Pr | 5/2+# |
| β+ | 131Nd | ||||||
| 132Pm | 61 | 71 | 131.93375(21)# | 6.2(6) s | β+ | 132Nd | (3+) |
| β+, p (5×10−5%) | 131Pr | ||||||
| 133Pm | 61 | 72 | 132.92978(5) | 15(3) s | β+ | 133Nd | (3/2+) |
| 133mPm | 130.4(10) keV | 10# s | β+ | 133Nd | (11/2-) | ||
| IT Isomeric transition An isomeric transition is a radioactive decay process that involves emission of a gamma ray from an atom where the nucleus is in an excited metastable state, referred to in its excited state, as a nuclear isomer.... |
133Pm | ||||||
| 134Pm | 61 | 73 | 133.92835(6) | 22(1) s | β+ | 134Nd | (5+) |
| 134mPm | 0(100)# keV | ~5 s | IT | 134Pm | (2+) | ||
| 135Pm | 61 | 74 | 134.92488(6) | 49(3) s | β+ | 135Nd | (5/2+,3/2+) |
| 135mPm | 50(100)# keV | 40(3) s | β+ | 135Nd | (11/2-) | ||
| 136Pm | 61 | 75 | 135.92357(8) | 107(6) s | β+ | 136Nd | (5-) |
| 136mPm | 130(120) keV | 47(2) s | β+ | 136Nd | (2+) | ||
| 137Pm | 61 | 76 | 136.920479(14) | 2# min | β+ | 137Nd | 5/2+# |
| 137mPm | 150(50) keV | 2.4(1) min | β+ | 137Nd | 11/2- | ||
| 138Pm | 61 | 77 | 137.919548(30) | 10(2) s | β+ | 138Nd | 1+# |
| 138mPm | 30(30) keV | 3.24(5) min | β+ | 138Nd | 5-# | ||
| 139Pm | 61 | 78 | 138.916804(14) | 4.15(5) min | β+ | 139Nd | (5/2)+ |
| 139mPm | 188.7(3) keV | 180(20) ms | IT (99.83%) | 139Pm | (11/2)- | ||
| β+ (.17%) | 139Nd | ||||||
| 140Pm | 61 | 79 | 139.91604(4) | 9.2(2) s | β+ | 140Nd | 1+ |
| 140mPm | 420(40) keV | 5.95(5) min | β+ | 140Nd | 8- | ||
| 141Pm | 61 | 80 | 140.913555(15) | 20.90(5) min | β+ | 141Nd | 5/2+ |
| 141m1Pm | 628.40(10) keV | 630(20) ns | 11/2- | ||||
| 141m2Pm | 2530.9(5) keV | >2 µs | |||||
| 142Pm | 61 | 81 | 141.912874(27) | 40.5(5) s | β+ | 142Nd | 1+ |
| 142mPm | 883.17(16) keV | 2.0(2) ms | IT | 142Pm | (8)- | ||
| 143Pm | 61 | 82 | 142.910933(4) | 265(7) d | β+ | 143Nd | 5/2+ |
| 144Pm | 61 | 83 | 143.912591(3) | 363(14) d | β+ | 144Nd | 5- |
| 144m1Pm | 840.90(5) keV | 780(200) ns | (9)+ | ||||
| 144m2Pm | 8595.8(22) keV | ~2.7 µs | (27+) | ||||
| 145Pm | 61 | 84 | 144.912749(3) | 17.7(4) a | EC Electron capture Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron and simultaneously emits a neutrino... |
145Nd | 5/2+ |
| α Alpha decay Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle and thereby transforms into an atom with a mass number 4 less and atomic number 2 less... (2.8×10−7%) |
141Pr | ||||||
| 146Pm | 61 | 85 | 145.914696(5) | 5.53(5) a | EC (66%) | 146Nd | 3- |
| β- (34%) | 146Sm | ||||||
| 147PmFission product Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The... |
61 | 86 | 146.9151385(26) | 2.6234(2) a | β- | 147Sm | 7/2+ |
| 148Pm | 61 | 87 | 147.917475(7) | 5.368(2) d | β- | 148Sm | 1- |
| 148mPm | 137.9(3) keV | 41.29(11) d | β- (95%) | 148Sm | 5-,6- | ||
| IT (5%) | 148Pm | ||||||
| 149Pm | 61 | 88 | 148.918334(4) | 53.08(5) h | β- | 149Sm |
7/2+ |
| 149mPm | 240.214(7) keV | 35(3) µs | 11/2- | ||||
| 150Pm | 61 | 89 | 149.920984(22) | 2.68(2) h | β- | 150Sm | (1-) |
| 151Pm | 61 | 90 | 150.921207(6) | 28.40(4) h | β- | 151Sm | 5/2+ |
| 152Pm | 61 | 91 | 151.923497(28) | 4.12(8) min | β- | 152Sm | 1+ |
| 152m1Pm | 140(90) keV | 7.52(8) min | 4- | ||||
| 152m2Pm | 250(150)# keV | 13.8(2) min | (8) | ||||
| 153Pm | 61 | 92 | 152.924117(12) | 5.25(2) min | β- | 153Sm | 5/2- |
| 154Pm | 61 | 93 | 153.92646(5) | 1.73(10) min | β- | 154Sm | (0,1) |
| 154mPm | 120(120) keV | 2.68(7) min | β- | 154Sm | (3,4) | ||
| 155Pm | 61 | 94 | 154.92810(3) | 41.5(2) s | β- | 155Sm | (5/2-) |
| 156Pm | 61 | 95 | 155.93106(4) | 26.70(10) s | β- | 156Sm | 4- |
| 157Pm | 61 | 96 | 156.93304(12) | 10.56(10) s | β- | 157Sm | (5/2-) |
| 158Pm | 61 | 97 | 157.93656(14) | 4.8(5) s | β- | 158Sm | |
| 159Pm | 61 | 98 | 158.93897(21)# | 1.47(15) s | β- | 159Sm | 5/2-# |
| 160Pm | 61 | 99 | 159.94299(32)# | 2# s | β- | 160Sm | |
| 161Pm | 61 | 100 | 160.94586(54)# | 700# ms | β- | 161Sm | 5/2-# |
| 162Pm | 61 | 101 | 161.95029(75)# | 500# ms | β- | 162Sm | |
| 163Pm | 61 | 102 | 162.95368(86)# | 200# ms | β- | 163Sm | 5/2-# |