Introduction
Group: None
Atomic Weight: 145
Period: 6
CAS Number: 7440-12-2
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
In 1902 Branner predicted the existence of an element between neodymium and samarium, and this was confirmed by Moseley in 1914. Unsuccessful searches were made for this predicted element over two decades, and various investigators proposed the names “illinium”, “florentium”, and “cyclonium” for this element. In 1941, workers at Ohio State University irradiated neodymium and praseodymium with neutrons, deuterons, and alpha particles, resp., 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 ionexchange chromatography. Their work was done by fission of uranium and by neutron bombardment of neodymium. These investigators named the newly discovered 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 reported to be 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. Thirty five isotopes and isomers of promethium, with atomic masses from 130 to 158 are now known. Promethium-145,with a half-life of 17.7 years, is the most useful. Promethium-145 has a specific activity of 940 Ci/g. 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 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. It is being used for fluorescent lighting starter sand coatings for self-luminous watch dials. 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. Promethium-147 is available upon special order from the Idaho National Engineering Laboratory, Idaho Falls, ID, or from the Westinghouse Hanford Co., Richland, WA. 1
Physical Properties
Melting Point:2* 1042 °C = 1315.15 K = 1907.6 °F
Electron Configuration: *[Xe] 6s2 4f5
n = 4
Boiling Point:2* 3000 °C = 3273.15 K = 5432 °F
Sublimation Point:2
Triple Point:2
Critical Point:2
Density:3 7.26 g/cm3
* - at 1 atm
Electron Configuration
Block: f
Highest Occupied Energy Level: 6
Valence Electrons: 2
Quantum Numbers:
ℓ = 3
mℓ = 1
ms = +½
Bonding
Ionization Potential
eV 4
kJ/mol
1
5.582
538.6
Ionization Potential
eV 4
kJ/mol
2
10.9
1051.7
Ionization Potential
eV 4
kJ/mol
3
22.3
2151.6
4
41.1
3965.5
Isotopes
Nuclide
Mass 5
Half-Life 5
Nuclear Spin 5
Binding Energy
126Pm
125.95752(54)#
0.5# s
1,015.84 MeV
127Pm
126.95163(64)#
1# s
5/2+#
1,023.91 MeV
128Pm
127.94842(43)#
1.0(3) s
6+#
1,041.29 MeV
129Pm
128.94316(43)#
3# s [>200 ns]
5/2+#
1,049.36 MeV
130Pm
129.94045(32)#
2.6(2) s
(5+,6+,4+)
1,057.44 MeV
131Pm
130.93587(21)#
6.3(8) s
5/2+#
1,074.82 MeV
132Pm
131.93375(21)#
6.2(6) s
(3+)
1,082.89 MeV
133Pm
132.92978(5)
15(3) s
(3/2+)
1,100.28 MeV
134Pm
133.92835(6)
22(1) s
(5+)
1,108.35 MeV
135Pm
134.92488(6)
49(3) s
(5/2+,3/2+)
1,116.42 MeV
136Pm
135.92357(8)
107(6) s
(5-)
1,124.49 MeV
137Pm
136.920479(14)
2# min
5/2+#
1,132.57 MeV
138Pm
137.919548(30)
10(2) s
1+#
1,149.95 MeV
139Pm
138.916804(14)
4.15(5) min
(5/2)+
1,158.02 MeV
140Pm
139.91604(4)
9.2(2) s
1+
1,166.09 MeV
141Pm
140.913555(15)
20.90(5) min
5/2+
1,174.17 MeV
142Pm
141.912874(27)
40.5(5) s
1+
1,182.24 MeV
143Pm
142.910933(4)
265(7) d
5/2+
1,190.31 MeV
144Pm
143.912591(3)
363(14) d
5-
1,198.38 MeV
145Pm
144.912749(3)
17.7(4) a
5/2+
1,206.45 MeV
146Pm
145.914696(5)
5.53(5) a
3-
1,214.52 MeV
147Pm
146.9151385(26)
2.6234(2) a
7/2+
1,222.59 MeV
148Pm
147.917475(7)
5.368(2) d
1-
1,230.66 MeV
149Pm
148.918334(4)
53.08(5) h
7/2+
1,238.74 MeV
150Pm
149.920984(22)
2.68(2) h
(1-)
1,237.49 MeV
151Pm
150.921207(6)
28.40(4) h
5/2+
1,245.56 MeV
152Pm
151.923497(28)
4.12(8) min
1+
1,253.63 MeV
153Pm
152.924117(12)
5.25(2) min
5/2-
1,261.71 MeV
154Pm
153.92646(5)
1.73(10) min
(0,1)
1,269.78 MeV
155Pm
154.92810(3)
41.5(2) s
(5/2-)
1,277.85 MeV
156Pm
155.93106(4)
26.70(10) s
4-
1,276.61 MeV
157Pm
156.93304(12)
10.56(10) s
(5/2-)
1,284.68 MeV
158Pm
157.93656(14)
4.8(5) s
1,292.75 MeV
159Pm
158.93897(21)#
1.47(15) s
5/2-#
1,300.82 MeV
160Pm
159.94299(32)#
2# s
1,299.58 MeV
161Pm
160.94586(54)#
700# ms
5/2-#
1,307.65 MeV
162Pm
161.95029(75)#
500# ms
1,306.40 MeV
163Pm
162.95368(86)#
200# ms
5/2-#
1,314.47 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 5
Abundance
Earth - Source Compounds: phosphates 6
Compounds
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
External Links:
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
Magazines:
(1) Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, pp 136-145.
(2) Folger, Tim. The Secret Ingredients of Everything. National Geographic, June 2011, pp 136-145.
Sources
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:24-4:25.
(2) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(8) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(9) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.