Introduction
Group: None
Atomic Weight: 239
Period: 7
CAS Number: 7440-07-5
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
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
Physical Properties
Melting Point:2* 640 °C = 913.15 K = 1184 °F
Electron Configuration: *[Rn] 7s2 5f6
n = 5
Electronegativity (Pauling scale):4 1.3
Specific Heat:
External Links:
Magazines:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:23.
Boiling Point:2* 3228 °C = 3501.15 K = 5842.4 °F
Sublimation Point:2
Triple Point:2
Critical Point:2
Density:3 19.7 g/cm3
* - at 1 atm
Electron Configuration
Block: f
Highest Occupied Energy Level: 7
Valence Electrons: 2
Quantum Numbers:
ℓ = 3
mℓ = 2
ms = +½
Bonding
Electropositivity (Pauling scale): 2.7
Ionization Potential
eV 5
kJ/mol
Ionization Potential
eV 5
kJ/mol
Ionization Potential
eV 5
kJ/mol
1
6.0262
581.4
Thermochemistry
Thermal Conductivity: 6.74 (W/m)/K, 27°C 6
Heat of Fusion: 2.84 kJ/mol 7 = 11.9 J/g
Heat of Vaporization: 344 kJ/mol 8 = 1439.3 J/g
State of Matter
Enthalpy of Formation (ΔHf°)9
Entropy (S°)9
Gibbs Free Energy (ΔGf°)9
(kcal/mol)
(kJ/mol)
(cal/K)
(J/K)
(kcal/mol)
(kJ/mol)
(s)
0
0
12.3
51.4632
0
0
Isotopes
Nuclide
Mass 10
Half-Life 10
Nuclear Spin 10
Binding Energy
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
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. 10
Abundance
Compounds
plutonium(II) oxide
plutonium(II) selenide
plutonium(II) sulfide
plutonium(III) bromide
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
(1) Biello, David. Trashing the "Element from Hell". Scientific American, July 2012, pp 19.
Sources
(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).