プルトニウム

導入

原子番号: 94
グループ: なし
原子量: 239
期間: 7
CAS番号: 7440-07-5

分類

カルコゲン
ハロゲン
希ガス
ランタノイド元素
アクチノイド元素
希土類元素
プラチナグループメタル
超ウラン
いいえ安定同位体ません
固体
液体
ガス
固体 (予測)

説明 • 用途/機能

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

物理的特性

融点:2*  640 °C = 913.15 K = 1184 °F
沸点:2* 3228 °C = 3501.15 K = 5842.4 °F
昇華点:2 
三重点:2 
臨界点:2 
密度:3  19.7 g/cm3

* - at 1 atm

電子構成

電子構成:  *[Rn] 7s2 5f6
ブロック: f
最高占有エネルギーレベル: 7
ヴァランス電子: 2

量子数:

n = 5
ℓ = 3
m = 2
ms = +½

ボンディング

電気陰性度 (ポーリングスケール):4 1.3
Electropositivity (ポーリングスケール): 2.7

イオン化ポテンシャル   eV 5  kJ/mol  
イオン化ポテンシャル   eV 5  kJ/mol  
イオン化ポテンシャル   eV 5  kJ/mol  
1 6.0262    581.4

熱化学

比熱: 
熱伝導率: 6.74 (W/m)/K, 27°C 6
融解熱: 2.84 kJ/mol 7 = 11.9 J/g
気化熱: 344 kJ/mol 8 = 1439.3 J/g
物質の状態 生成エンタルピー (ΔHf°)9 エントロピ (S°)9 ギブズ自由エネルギー (ΔGf°)9
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 12.3 51.4632 0 0

同位体

核種 質量 10 人生の半分 10 核スピン 10 結合エネルギー
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
値は、#は、純粋に実験データから派生しますが、少なくとも部分的に体系的な傾向からしていないとマーク。弱い代入引数は括弧で囲まれていてスピン。 10

豊富

化合物

安全情報


安全データシート - ACI Alloys, Inc.

詳細については

外部リンク:

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

ソース

(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).