PLUTÔNIO

Introdução

Número atômico: 94
Grupo: Nenhum
Peso atômico: 239
Período: 7
Número CAS: 7440-07-5

Classificação

Calcogênio
halogênio
Gás nobre
Lantanóides
Actinóide
Terra-rara
Platinum Metal Group
Transuranium
Não Isótopos Estáveis
Sólido
Líquido
Gás
Sólido (previsto)

Descrição • Usos / Função

Plutonium was the second transuranium element of the actinide series to be discovered. The isotope plutonium-238 was produced in 1940 by Seaborg, McMillan, Kennedy, and Wahl by deuteron bombardment of uranium in the 60-inch cyclotron at Berkeley, California. Plutonium also exists in trace quantities in naturally occurring uranium ores. It is formed in much the same manner as neptunium, by irradiation of natural uranium with the neutrons which are present. By far of greatest importance is the isotope plutonium-239, with a half-life of 24,100 years, produced in extensive quantities in nuclear reactors from natural uranium. First, uranium-238 picks up a neutron to give uranium-239, which then undergoes two successive beta decays, to produce neptunium-239 and finally plutonium-239.. Eighteen isotopes of plutonium are now known. Plutonium has assumed the position of dominant importance among the transuranium elements because of its successful use as an explosive ingredient in nuclear weapons and the place which it holds as a key material in the development of industrial use of nuclear power. One kilogram is equivalent to about 22 million kilowatt hours of heat energy. The complete detonation of a kilogram of plutonium produces an explosion equal to about 20,000 tons of chemical explosive. Its importance depends on the nuclear property of being readily fissionable with neutrons and its availability in quantity. The world’s nuclear-power reactors are now producing about 20,000 kg of plutonium/yr. By 1982 it was estimated that about 300,000 kg had accumulated. The various nuclear applications of plutonium are well known. Plutonium-238 has been used in the Apollo lunar missions to power seismic and other equipment on the lunar surface. As with neptunium and uranium, plutonium metal can be prepared by reduction of the trifluoride with alkaline-earth metals. The metal has a silvery appearance and takes on a yellow tarnish when slightly oxidized. It is chemically reactive. A relatively large piece of plutonium is warm to the touch because of the energy given off in alpha decay. Larger pieces will produce enough heat to boil water. The metal readily dissolves in concentrated hydrochloric acid, hydroiodic acid, or perchloric acid with formation of the Pu+3 ion. The metal exhibits six allotropic modifications having various crystalline structures. The densities of these vary from 16.00 to 19.86 g/cm3. Plutonium also exhibits four ionic valence states in aqueous solutions: Pu+3(blue lavender), Pu+4 (yellow brown), PuO+ (pink?), and PuO+2 (pink orange). The ion PuO+ is unstable in aqueous solutions, disproportionating into Pu+4 and PuO+2. The Pu+4 thus formed, however, oxidizes the PuO+ into PuO+2, itself being reduced to Pu+3, giving finally Pu+3 and PuO+2. Plutonium forms binary compounds with oxygen: PuO, PuO2, and intermediate oxides of variable composition; with the halides: Puf3, Puf4, PuCl3, PuBr3, PuI3; with carbon, nitrogen, and silicon: PuC, PuN, PuSi2. Oxyhalides are also well known: PuOCl, PuOBr, PuOI. Because of the high rate of emission of alpha particles and the element being specifically absorbed by bone marrow, plutonium, as well as all of the other transuranium elements except neptunium, are radiological poisons and must be handled with very special equipment and precautions. Plutonium is a very dangerous radiological hazard. Precautions must also be taken to prevent the unintentional formation of a critical mass. Plutonium in liquid solution is more likely to become critical than solid plutonium. The shape of the mass must also be considered where criticality is concerned. Plutonium-238 is available to authorized users from the O.R.N.L. at a cost of about $7.50/mg (97%) plus packing costs of $1250 per package. 1

Propriedades físicas

Ponto de fusão:2*  640 °C = 913.15 K = 1184 °F
Ponto de ebulição:2* 3228 °C = 3501.15 K = 5842.4 °F
Ponto de sublimação:2 
Ponto Triplo:2 
Ponto crítico:2 
Densidade:3  19.7 g/cm3

* - at 1 atm

Configuração Electron

Configuração Electron:  *[Rn] 7s2 5f6
Quadra: f
Mais alto nível de energia Ocupado: 7
Elétrons de valência: 2

Números quânticos:

n = 5
ℓ = 3
m = 2
ms = +½

Colagem

Eletronegatividade (escala Pauling):4 1.3
Electropositivity (escala Pauling): 2.7

potencial de ionização   eV 5  kJ/mol  
potencial de ionização   eV 5  kJ/mol  
potencial de ionização   eV 5  kJ/mol  
1 6.0262    581.4

Termoquímica

Calor específico: 
Condutividade térmica: 6.74 (W/m)/K, 27°C 6
Calor de fusão: 2.84 kJ/mol 7 = 11.9 J/g
Calor da vaporização: 344 kJ/mol 8 = 1439.3 J/g
Estado da matéria Entalpia de formação (ΔHf°)9 entropia (S°)9 Gibbs Energia Livre (ΔGf°)9
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 12.3 51.4632 0 0

isótopos

nuclide Massa 10 Meia vida 10 spin nuclear 10 Energia de ligação
228Pu 228.03874(3) 1.1(+20-5) s 0+ 1,738.77 MeV
229Pu 229.04015(6) 120(50) s 3/2+# 1,737.53 MeV
230Pu 230.039650(16) 1.70(17) min 0+ 1,754.91 MeV
231Pu 231.041101(28) 8.6(5) min 3/2+# 1,753.67 MeV
232Pu 232.041187(19) 33.7(5) min 0+ 1,761.74 MeV
233Pu 233.04300(5) 20.9(4) min 5/2+# 1,769.81 MeV
234Pu 234.043317(7) 8.8(1) h 0+ 1,777.89 MeV
235Pu 235.045286(22) 25.3(5) min (5/2+) 1,785.96 MeV
236Pu 236.0460580(24) 2.858(8) a 0+ 1,794.03 MeV
237Pu 237.0484097(24) 45.2(1) d 7/2- 1,802.10 MeV
238Pu 238.0495599(20) 87.7(1) a 0+ 1,810.17 MeV
239Pu 239.0521634(20) 24.11(3)E+3 a 1/2+ 1,808.93 MeV
240Pu 240.0538135(20) 6561(7) a 0+ 1,817.00 MeV
241Pu 241.0568515(20) 14.290(6) a 5/2+ 1,825.07 MeV
242Pu 242.0587426(20) 3.75(2)E+5 a 0+ 1,833.14 MeV
243Pu 243.062003(3) 4.956(3) h 7/2+ 1,831.90 MeV
244Pu 244.064204(5) 8.00(9)E+7 a 0+ 1,839.97 MeV
245Pu 245.067747(15) 10.5(1) h (9/2-) 1,848.04 MeV
246Pu 246.070205(16) 10.84(2) d 0+ 1,846.80 MeV
247Pu 247.07407(32)# 2.27(23) d 1/2+# 1,854.87 MeV
Os valores marcados # não são puramente derivado a partir de dados experimentais, mas, pelo menos, parcialmente a partir de tendências sistemáticas. Gira com argumentos de atribuição fracos estão entre parênteses. 10

Abundância

compostos

Informação de Segurança


Material Safety Data Sheet - ACI Alloys, Inc.

Para maiores informações

Links externos:

revistas:
(1) Biello, David. Trashing the "Element from Hell". Scientific American, July 2012, pp 19.

Fontes

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:23.
(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) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(9) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(10) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).