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Isotopes of fermium



Fermium (Fm) has no stable isotopes. A standard atomic mass cannot be given.

Additional recommended knowledge

Fermium has also been called eka-erbium and centurium.

Table

nuclide
symbol
Z(p) N(n)  
isotopic mass (u)
 
half-life nuclear
spin
representative
isotopic
composition
(mole fraction)
range of natural
variation
(mole fraction)
excitation energy
242Fm 100 142 242.07343(43)# 0.8(2) ms 0+
243Fm 100 143 243.07435(23)# 210(60) ms [0.18(+8-4) s] 7/2-#
244Fm 100 144 244.07408(30)# 3.3(5) ms 0+
245Fm 100 145 245.07539(30)# 4.2(13) s 1/2+#
246Fm 100 146 246.07530(4) 1.1(2) s 0+
247Fm 100 147 247.07685(15)# 29(1) s (7/2+)
248Fm 100 148 248.077195(13) 36(2) s 0+
249Fm 100 149 249.07903(11)# 2.6(7) min (7/2+)#
250Fm 100 150 250.079521(13) 30(3) min 0+
250mFm 1500(300)# keV 1.8(1) s 7,8#
251Fm 100 151 251.081575(9) 5.30(8) h (9/2-)
251mFm 191(2) keV 15.2(23) µs (5/2+)
252Fm 100 152 252.082467(6) 25.39(4) h 0+
253Fm 100 153 253.085185(4) 3.00(12) d (1/2)+
254Fm 100 154 254.0868542(30) 3.240(2) h 0+
255Fm 100 155 255.089962(5) 20.07(7) h 7/2+
256Fm 100 156 256.091773(8) 157.6(13) min 0+
257Fm 100 157 257.095105(7) 100.5(2) d (9/2+)
258Fm 100 158 258.09708(22)# 370(14) µs 0+
259Fm 100 159 259.1006(3)# 1.5(3) s 3/2+#
260Fm 100 160 260.10268(54)# 1# min 0+

Notes

  • 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.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.
  • The isotopes denoted by an isotope number with an "m" are metastable_isomers.

References

  • Isotope masses from Ame2003 Atomic Mass Evaluation by G. Audi, A.H. Wapstra, C. Thibault, J. Blachot and O. Bersillon in Nuclear Physics A729 (2003).
  • Isotopic compositions and standard atomic masses from Atomic weights of the elements. Review 2000 (IUPAC Technical Report). Pure Appl. Chem. Vol. 75, No. 6, pp. 683-800, (2003) and Atomic Weights Revised (2005).
  • Half-life, spin, and isomer data selected from these sources. Editing notes on this article's talk page.
    • Audi, Bersillon, Blachot, Wapstra. The Nubase2003 evaluation of nuclear and decay properties, Nuc. Phys. A 729, pp. 3-128 (2003).
    • National Nuclear Data Center, Brookhaven National Laboratory. Information extracted from the NuDat 2.1 database (retrieved Sept. 2005).
    • David R. Lide (ed.), Norman E. Holden in CRC Handbook of Chemistry and Physics, 85th Edition, online version. CRC Press. Boca Raton, Florida (2005). Section 11, Table of the Isotopes.


Isotopes of einsteinium Isotopes of fermium Isotopes of mendelevium
Index to isotope pages
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Isotopes_of_fermium". A list of authors is available in Wikipedia.
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