Periodic Table of Elements

Fm - Fermium

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Nuclides / Isotopes

Nuc-
lide
Atomic
Mass
NNAbun
%
SpinHalf LifeDMDTBR
%
Decay
Energy
(MeV)
Fm242242.073142Syn0+0.8msSF   
Fm243243.075143Syn 0.18sαCf239<=1008.690
 0.18sSF <=0.368.690
Fm244244.074144Syn0+3.3msSF <=100 
Fm245245.075145Syn 4.2sαCf241<=1008.440
 4.2sSF <=0.11 
Fm246246.0753146Syn0+1.1sαCf242928.374
 1.1sSF 8 
 1.1sεEs246<=12.160
Fm247247.077147Syn 35sαCf243>=508.190
 35sεEs247<=508.190
Fm248248.0772148Syn0+36sαCf244998.002
 36sεEs248~11.600
 36sSF ~0.05 
Fm249249.079149Syn7/2+2.6mεEs249~852.440
 2.6mαCf245~157.810
 2.6mα   
 2.6mε   
Fm250250.0795150Syn0+30mαCf246>907.557
 30mεEs250<100.800
 30mSF ~0.00060.800
meta state 1.000MeVSyn 1.8sITFm250>801.000
 1.8sSF  1.000
Fm251251.0816151Syn9/2-5.3hεEs25198.21.474
 5.3hαCf2471.87.425
Fm252252.0825152Syn0+25.39hSF 0.0023 
 25.39hαCf248 7.153
Fm253253.0852153Syn1/2+3dεEs253880.333
 3dαCf249127.197
Fm254254.0869154Syn0+3.24hαCf25099.947.307
 3.24hSF 0.06 
Fm255255.09155Syn7/2+20.07hSF 0.00002 
 20.07hαCf251 7.241
Fm256256.0918156Syn0+157.6mSF 91.9 
 157.6mαCf2528.17.027
Fm257257.0951157Syn9/2+100.5dαCf25399.796.864
 100.5dSF 0.21 
Fm258258.097158Syn0+370usSF   
Fm259259.101159Syn 1.5sSF   
Fm260 160Syn0+~4ms    
NuclidePotential Parent Nuclides
Fm242None known
Fm243None known
Fm244None known
Fm245None known
Fm246No250 (Syn)
Fm247No251 (Syn)
Fm248Md248 (Syn) No252 (Syn)
Fm249Md249 (Syn) No253 (Syn)
Fm250Fm250m (Syn) Md250 (Syn) No254 (Syn)
meta state 1.000MeVNone known
Fm251Md251 (Syn) No255 (Syn)
Fm252Es252 (Syn) Md252 (Syn) No256 (Syn)
Fm253Md253 (Syn) No257 (Syn)
Fm254Es254 (Syn) Es254m (Syn) Md254 (Syn) No258 (Syn)
Fm255Es255 (Syn) Md255 (Syn) No259 (Syn)
Fm256Es256 (Syn) Es256m (Syn) Md256 (Syn)
Fm257Md257 (Syn)
Fm258Md258 (Syn)
Fm259None known
Fm260Md260 (Syn)

Key:

  • NN = Number of Neutrons
  • Abun % = Natural Abundance (as a percentage)
  • Syn = Synthetic Nuclide (does not occur in nature)
  • DM = Decay Mode
    α = Alpha emission
    β- = Beta emission
    β- β- = Double beta decay
    β+ = Positron emission
    ε = Electron Capture
    IT = Isomeric Transition
    N = Neutron emission
    P = Proton emission
    SF = Spontaneous Fission
  • DT = Decays To
  • BR % = Branch Ratio (as a percentage)

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References

A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.

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