PROMETEO

introduzione

Numero atomico: 61
Gruppo: Nessuna
Peso atomico: 145
Periodo: 6
Numero CAS: 7440-12-2

Classificazione

Metallo
Metalloide
simile a metallo
metallo alcalino
Alkali terroso
Metallo di transizione
calcogeno
alogena
Gas nobile
Lanthanoid
Actinoid
Terre rare
Platinum Metal Group
transuranici
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)

Descrizione • Usi / Funzione

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

Proprietà fisiche

Punto di fusione:2*  1042 °C = 1315.15 K = 1907.6 °F
Punto di ebollizione:2* 3000 °C = 3273.15 K = 5432 °F
sublimazione Point:2 
Triple Point:2 
Punto critico:2 
Densità:3  7.26 g/cm3

* - at 1 atm

configurazione elettronica

configurazione elettronica:  *[Xe] 6s2 4f5
Bloccare: f
Più alto livello di energia Occupato: 6
Elettroni di valenza: 2

numeri quantici:

n = 4
ℓ = 3
m = 1
ms = +½

bonding

potenziale di ionizzazione   eV 4  kJ/mol  
1 5.582    538.6
potenziale di ionizzazione   eV 4  kJ/mol  
2 10.9    1051.7
potenziale di ionizzazione   eV 4  kJ/mol  
3 22.3    2151.6
4 41.1    3965.5

isotopi

nuclide Massa 5 Metà vita 5 spin nucleare 5 Energia di legame
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
I valori assegnati # non sono puramente derivati ​​da dati sperimentali, ma almeno parzialmente da tendenze sistematiche. Gira con argomenti di assegnazione deboli sono racchiusi tra parentesi. 5

Abbondanza

Terra - composti di origine: phosphates 6

Composti

Informazioni sulla sicurezza


Scheda di sicurezza - ACI Alloys, Inc.

Per maggiori informazioni

Link esterno:

riviste:
(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.

fonti

(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.