Skip to Main Content

About Promethium

Promethium Bohr

All of promethium’s isotopes are radioactive and have short half-lives, so appreciable amounts are not found in natural sources. The existence of an unknown element with atomic number 61 was predicted in 1914 by Henry Mosley, but the metal was not successfully produced and fully characterized until 1945. This was accomplished by Jacob A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell at Oak Ridge National Laboratory by separating and analyzing fission products of uranium. The name was derived from the Titan in Greek mythology who stole fire from Mount Olympus to give to humans, Prometheus. Since the element can only be obtained from a lab, it has few applications. The only isotope of promethium used outside of research is promethium-147, which is produced and used in very small (milligram) quantities in atomic batteries and signal lights containing phosphors that emit light in response to absorption of radiation emitted by the isotope. Since this relatively stable isotope emits x-rays, it could theoretically be used for portable x-ray sources.

Promethium Properties

Promethium Bohr ModelPromethium is a Block F, Group 3, Period 6 element. The number of electrons in each of Promethium's shells is 2, 8, 18, 23, 8, 2 and its electron configuration is [Xe] 4f5 6s2. The promethium atom has a radius of and it's Van der Waals radius is In its elemental form, CAS 7440-12-2, promethium has a metalic appearance. Promethium was discovered by Chien Shiung Wu, Emilio Segrè, and Hans Bethe in 1942. It was first isolated by J. A. Marinsky, Lawrence Glendenin and Charles D. Coryell in 1945. The element name comes from Greek mythology after the titan, Prometheus, who stole the fire of Zeus and gave it to mankind.

Promethium is radioactive. Promethium information, including technical data, properties, and other useful facts are specified below. Scientific facts such as the atomic structure, ionization energy, abundance on Earth, conductivity, and thermal properties are included.

Symbol: Pm
Atomic Number: 61
Atomic Weight: 145
Element Category: Lanthanide
Group, Period, Block: n/a, 6, f
Color: silvery-white/ metallic
Other Names: Prometio, Promécio
Melting Point: 1042°C, 1907.6°F, 1315.15 K
Boiling Point: 3000°C, 5432°F, 3273.15 K
Density: 7.26 g·cm3
Liquid Density @ Melting Point: N/A
Density @ 20°C: 7.220 g/cm3
Density of Solid: 7264 kg·m3
Specific Heat: N/A
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): about 7.7
Heat of Vaporization (kJ·mol-1): 290
Heat of Atomization (kJ·mol-1): about 350
Thermal Conductivity: 17.9 W·m-1·K-1
Thermal Expansion: (r.t.) ( poly) est. 11 µm/(m·K)
Electrical Resistivity: (r.t.) est. 0.75 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: N/A
Young's Modulus: (form) est. 46 GPa
Shear Modulus: ( form) est. 18 GPa
Bulk Modulus: ( form) est. 33 GPa
Poisson Ratio: ( form) est. 0.28
Mohs Hardness: N/A
Vickers Hardness: N/A
Brinell Hardness: N/A
Speed of Sound: N/A
Pauling Electronegativity: N/A
Sanderson Electronegativity: N/A
Allred Rochow Electronegativity: 1.07
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: N/A
Reflectivity (%): N/A
Refractive Index: N/A
Electrons: 61
Protons: 61
Neutrons: 84
Electron Configuration: [Xe] 4f5 6s2
Atomic Radius: 183 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 199 pm
Covalent Radius (Å): 1.86
Van der Waals Radius: 236 pm
Oxidation States: 3 (mildly basic oxide)
Phase: Solid
Crystal Structure: hexagonal
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) Unknown
1st Ionization Energy: 538.39 kJ·mol-1
2nd Ionization Energy: 1051.70 kJ·mol-1
3rd Ionization Energy: 2151.64 kJ·mol-1
CAS Number: 7440-12-2
EC Number: N/A
MDL Number: N/A
Beilstein Number: N/A
SMILES Identifier: [Pm]
InChI Identifier: InChI=1S/Pm
PubChem CID: 23944
ChemSpider ID: 22386
Earth - Total: N/A
Mercury - Total: N/A
Venus - Total: N/A
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: N/A
Earth -  Crust (Crustal Rocks), ppb by atoms: N/A
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: N/A
Meterorite (Carbonaceous), ppb by atoms: N/A
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: N/A
Universe, ppb by atom: N/A
Discovered By: Chien Shiung Wu, Emilio Segrè, Hans Bethe
Discovery Date: 1942
First Isolation: Charles D. Coryell, Jacob A. Marinsky, Lawrence E. Glendenin, Harold G. Richter (1945)

Promethium Isotopes

Promethium (Pm) does not exist in nature (except in trace quantities from spontaneous fission and alpha decay of 151Eu). It has no stable isotopes.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
126Pm125.95752(54)#0.5# sUnknownN/AN/A996.05-
127Pm126.95163(64)#1# sUnknown5/2+#N/A1004.13-
128Pm127.94842(43)#1.0(3) sß+ to 128Nd; p to 127Nd6+#N/A1021.53-
129Pm128.94316(43)#3# s [>200 ns]ß+ to 129Nd5/2+#N/A1029.61-
130Pm129.94045(32)#2.6(2) sß+ to 130Nd; ß+ + p to 129Pr(5+,6+,4+)N/A1037.68-
131Pm130.93587(21)#6.3(8) sß+ + p to 130Pr; ß+ to 131Nd5/2+#N/A1055.08-
132Pm131.93375(21)#6.2(6) sß+ to 132Nd; ß+ + p to 131Pr(3+)N/A1063.16-
133Pm132.92978(5)15(3) sß+ to 133Nd(3/2+)N/A1080.55-
134Pm133.92835(6)22(1) sß+ to 134Nd(5+)N/A1088.63-
135Pm134.92488(6)49(3) sß+ to 135Nd(5/2+,3/2+)N/A1096.71-
136Pm135.92357(8)107(6) sß+ to 136Nd(5-)N/A1104.79-
137Pm136.920479(14)2# minß+ to 137Nd5/2+#N/A1112.87-
138Pm137.919548(30)10(2) sß+ to 138Nd1+#N/A1130.26-
139Pm138.916804(14)4.15(5) minß+ to 139Nd(5/2)+N/A1138.34-
140Pm139.91604(4)9.2(2) sß+ to 140Nd1+N/A1146.42-
141Pm140.913555(15)20.90(5) minß+ to 141Nd5/2+N/A1154.5-
142Pm141.912874(27)40.5(5) sß+ to 142Nd1+N/A1162.58-
143Pm142.910933(4)265(7) dEC to 143Nd5/2+3.81170.66-
144Pm143.912591(3)363(14) dEC to 144Nd5-1.71178.73-
145Pm144.912749(3)17.7(4) yEC to 145Nd; a to 141Pr5/2+N/A1186.81-
146Pm145.914696(5)5.53(5) yEC to 146Nd; ß- to 146Sm3-N/A1194.89-
147Pm146.9151385(26)2.6234(2) yß- to 147Sm7/2+2.61202.97-
148Pm147.917475(7)5.368(2) dß- to 148Sm1-21211.05-
149Pm148.918334(4)53.08(5) hß- to 149Sm7/2+3.31219.13-
150Pm149.920984(22)2.68(2) hß- to 150Sm(1-)N/A1217.89-
151Pm150.921207(6)28.40(4) hß- to 151Sm5/2+1.81225.97-
152Pm151.923497(28)4.12(8) minß- to 152Sm1+N/A1234.05-
153Pm152.924117(12)5.25(2) minß- to 153Sm5/2-N/A1242.13-
154Pm153.92646(5)1.73(10) minß- to 154Sm(0,1)N/A1250.21-
155Pm154.92810(3)41.5(2) sß- to 155Sm(5/2-)N/A1258.28-
156Pm155.93106(4)26.70(10) sß- to 156Sm4-N/A1257.05-
157Pm156.93304(12)10.56(10) sß- to 157Sm(5/2-)N/A1265.13-
158Pm157.93656(14)4.8(5) sß- to 158SmN/AN/A1273.2-
159Pm158.93897(21)#1.47(15) sß- to 159Sm5/2-#N/A1281.28-
160Pm159.94299(32)#2# sß- to 160SmN/AN/A1280.05-
161Pm160.94586(54)#700# msß- to 161Sm5/2-#N/A1288.12-
162Pm161.95029(75)#500# msß- to 162SmN/AN/A1286.89-
163Pm162.95368(86)#200# msß- to 163Sm5/2-#N/A1294.96-