介绍
组: 没有
原子量: 257
期: 7
CAS号码: 7440-72-4
分类
描述 • 用途/功能
Fermium, the eighth transuranium element of the actinide series to be discovered, was identified by Ghiorso and co-workers in 1952 in the debris from a thermonuclear explosion in the Pacific in work involving the University of California Radiation Laboratory, the Argonne National Laboratory, and the Los Alamos Scientific Laboratory. The isotope produced was the 20-hour 255Fm. During 1953 and early 1954, while discovery of elements 99 and 100 was withheld from publication for security reasons, a group from the Nobel Institute of Physics in Stockholm bombarded 238U with 16O ions, and isolated a 30-min a-emitter, which they ascribed to 250Fm, without claiming discovery of the element. This isotope has since been identified positively, and the 30-min half-life confirmed. The chemical properties of fermium have been studied solely with tracer amounts, and in normal aqueous media only the (III) oxidation state appears to exist. The isotope 254Fm and heavier isotopes can be produced by intense neutron irradiation of lower elements such as plutonium by a process of successive neutron capture interspersed with beta decays until these mass numbers and atomic numbers are reached. Twenty isotopes and isomers of fermium are known to exist. 257Fm, with a half-life of about 100.5 days, is the longest lived. 250Fm, with a half-life of 30 min, has been shown to be a product of decay of Element 254No. It was by chemical identification of 250Fm that production of nobelium was confirmed. 1
物理性能
熔点:2* 1527 °C = 1800.15 K = 2780.6 °F
电子组态: *[Rn] 7s2 5f12
n = 5
沸点:2*
升华点:2
三相点:2
临界点:2
密度: g/cm3
* - at 1 atm
电子组态
块: f
最高占据能级: 7
价电子: 2
量子数:
ℓ = 3
mℓ = 1
ms = -½
粘接
电离能
eV 3
kJ/mol
电离能
eV 3
kJ/mol
电离能
eV 3
kJ/mol
1
6.5
627.2
同位素
核素
块 4
半衰期 4
核自旋 4
结合能
242Fm
242.07343(43)#
0.8(2) ms
0+
1,809.82 MeV
243Fm
243.07435(23)#
210(60) ms [0.18(+8-4) s]
7/2-#
1,817.89 MeV
244Fm
244.07408(30)#
3.3(5) ms
0+
1,825.96 MeV
245Fm
245.07539(30)#
4.2(13) s
1/2+#
1,834.03 MeV
246Fm
246.07530(4)
1.1(2) s
0+
1,842.10 MeV
247Fm
247.07685(15)#
29(1) s
(7/2+)
1,850.17 MeV
248Fm
248.077195(13)
36(2) s
0+
1,858.24 MeV
249Fm
249.07903(11)#
2.6(7) min
(7/2+)#
1,866.32 MeV
250Fm
250.079521(13)
30(3) min
0+
1,874.39 MeV
251Fm
251.081575(9)
5.30(8) h
(9/2-)
1,873.14 MeV
252Fm
252.082467(6)
25.39(4) h
0+
1,881.21 MeV
253Fm
253.085185(4)
3.00(12) d
(1/2)+
1,889.29 MeV
254Fm
254.0868542(30)
3.240(2) h
0+
1,897.36 MeV
255Fm
255.089962(5)
20.07(7) h
7/2+
1,905.43 MeV
256Fm
256.091773(8)
157.6(13) min
0+
1,904.19 MeV
257Fm
257.095105(7)
100.5(2) d
(9/2+)
1,912.26 MeV
258Fm
258.09708(22)#
370(14) μs
0+
1,920.33 MeV
259Fm
259.1006(3)#
1.5(3) s
3/2+#
1,919.08 MeV
260Fm
260.10268(54)#
1# min
0+
1,927.16 MeV
值标记＃不是纯粹从实验数据得出，但至少部分来自系统的发展趋势。旋转弱任务参数都包含在括号中。 4
丰富
安全信息
材料安全数据表 - ACI Alloys, Inc.
了解更多信息
外部链接:
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
来源
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:12.
(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, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(5) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(7) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).