Promethium (Pm) | AMERICAN ELEMENTS ®

About Promethium

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 Model Promethium 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 183.pm and its Van der Waals radius is 236.pm. In its elemental form, CAS 7440-12-2, promethium has a metallic 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.

General Properties

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

Physical Properties

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

Chemical Properties

Electrons:	61
Protons:	61
Neutrons:	84
Electron Configuration:	[Xe] 4f⁵ 6s²
Atomic Radius:	183 pm
Atomic Radius, non-bonded (Å):	2.38
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
1^st Ionization Energy:	538.39 kJ·mol^-1
2^nd Ionization Energy:	1051.70 kJ·mol^-1
3^rd Ionization Energy:	2151.64 kJ·mol^-1

Identifiers

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
InChI Key:	VQMWBBYLQSCNPO-UHFFFAOYSA-N
PubChem CID:	23944
ChemSpider ID:	22386

Abundance

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

History

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)
¹²⁶Pm	125.95752(54)#	0.5# s	Unknown	N/A	N/A	996.05	-
¹²⁷Pm	126.95163(64)#	1# s	Unknown	5/2+#	N/A	1004.13	-
¹²⁸Pm	127.94842(43)#	1.0(3) s	ß⁺ to ¹²⁸Nd; p to ¹²⁷Nd	6+#	N/A	1021.53	-
¹²⁹Pm	128.94316(43)#	3# s [>200 ns]	ß⁺ to ¹²⁹Nd	5/2+#	N/A	1029.61	-
¹³⁰Pm	129.94045(32)#	2.6(2) s	ß⁺ to ¹³⁰Nd; ß⁺ + p to ¹²⁹Pr	(5+,6+,4+)	N/A	1037.68	-
¹³¹Pm	130.93587(21)#	6.3(8) s	ß⁺ + p to ¹³⁰Pr; ß⁺ to ¹³¹Nd	5/2+#	N/A	1055.08	-
¹³²Pm	131.93375(21)#	6.2(6) s	ß⁺ to ¹³²Nd; ß⁺ + p to ¹³¹Pr	(3+)	N/A	1063.16	-
¹³³Pm	132.92978(5)	15(3) s	ß⁺ to ¹³³Nd	(3/2+)	N/A	1080.55	-
¹³⁴Pm	133.92835(6)	22(1) s	ß⁺ to ¹³⁴Nd	(5+)	N/A	1088.63	-
¹³⁵Pm	134.92488(6)	49(3) s	ß⁺ to ¹³⁵Nd	(5/2+,3/2+)	N/A	1096.71	-
¹³⁶Pm	135.92357(8)	107(6) s	ß⁺ to ¹³⁶Nd	(5-)	N/A	1104.79	-
¹³⁷Pm	136.920479(14)	2# min	ß⁺ to ¹³⁷Nd	5/2+#	N/A	1112.87	-
¹³⁸Pm	137.919548(30)	10(2) s	ß⁺ to ¹³⁸Nd	1+#	N/A	1130.26	-
¹³⁹Pm	138.916804(14)	4.15(5) min	ß⁺ to ¹³⁹Nd	(5/2)+	N/A	1138.34	-
¹⁴⁰Pm	139.91604(4)	9.2(2) s	ß⁺ to ¹⁴⁰Nd	1+	N/A	1146.42	-
¹⁴¹Pm	140.913555(15)	20.90(5) min	ß⁺ to ¹⁴¹Nd	5/2+	N/A	1154.5	-
¹⁴²Pm	141.912874(27)	40.5(5) s	ß⁺ to ¹⁴²Nd	1+	N/A	1162.58	-
¹⁴³Pm	142.910933(4)	265(7) d	EC to ¹⁴³Nd	5/2+	3.8	1170.66	-
¹⁴⁴Pm	143.912591(3)	363(14) d	EC to ¹⁴⁴Nd	5-	1.7	1178.73	-
¹⁴⁵Pm	144.912749(3)	17.7(4) y	EC to ¹⁴⁵Nd; a to ¹⁴¹Pr	5/2+	N/A	1186.81	-
¹⁴⁶Pm	145.914696(5)	5.53(5) y	EC to ¹⁴⁶Nd; ß^- to ¹⁴⁶Sm	3-	N/A	1194.89	-
¹⁴⁷Pm	146.9151385(26)	2.6234(2) y	ß^- to ¹⁴⁷Sm	7/2+	2.6	1202.97	-
¹⁴⁸Pm	147.917475(7)	5.368(2) d	ß^- to ¹⁴⁸Sm	1-	2	1211.05	-
¹⁴⁹Pm	148.918334(4)	53.08(5) h	ß^- to ¹⁴⁹Sm	7/2+	3.3	1219.13	-
¹⁵⁰Pm	149.920984(22)	2.68(2) h	ß^- to ¹⁵⁰Sm	(1-)	N/A	1217.89	-
¹⁵¹Pm	150.921207(6)	28.40(4) h	ß^- to ¹⁵¹Sm	5/2+	1.8	1225.97	-
¹⁵²Pm	151.923497(28)	4.12(8) min	ß^- to ¹⁵²Sm	1+	N/A	1234.05	-
¹⁵³Pm	152.924117(12)	5.25(2) min	ß^- to ¹⁵³Sm	5/2-	N/A	1242.13	-
¹⁵⁴Pm	153.92646(5)	1.73(10) min	ß^- to ¹⁵⁴Sm	(0,1)	N/A	1250.21	-
¹⁵⁵Pm	154.92810(3)	41.5(2) s	ß^- to ¹⁵⁵Sm	(5/2-)	N/A	1258.28	-
¹⁵⁶Pm	155.93106(4)	26.70(10) s	ß^- to ¹⁵⁶Sm	4-	N/A	1257.05	-
¹⁵⁷Pm	156.93304(12)	10.56(10) s	ß^- to ¹⁵⁷Sm	(5/2-)	N/A	1265.13	-
¹⁵⁸Pm	157.93656(14)	4.8(5) s	ß^- to ¹⁵⁸Sm	N/A	N/A	1273.2	-
¹⁵⁹Pm	158.93897(21)#	1.47(15) s	ß^- to ¹⁵⁹Sm	5/2-#	N/A	1281.28	-
¹⁶⁰Pm	159.94299(32)#	2# s	ß^- to ¹⁶⁰Sm	N/A	N/A	1280.05	-
¹⁶¹Pm	160.94586(54)#	700# ms	ß^- to ¹⁶¹Sm	5/2-#	N/A	1288.12	-
¹⁶²Pm	161.95029(75)#	500# ms	ß^- to ¹⁶²Sm	N/A	N/A	1286.89	-
¹⁶³Pm	162.95368(86)#	200# ms	ß^- to ¹⁶³Sm	5/2-#	N/A	1294.96	-