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Isotopes of the Element Mendelevium

[Click for Main Data]

Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information.

Naturally Occurring Isotopes

Mendelevium has no naturally occurring isotopes.

Known Isotopes

Mass NumberHalf-lifeDecay ModeBranching Percentage
2450.90 millisecondsAlpha DecayNo Data Available
Spontaneous FissionNo Data Available
245m0.35 secondsElectron CaptureNo Data Available
Alpha DecayNo Data Available
2460.9 secondsAlpha Decay100.00%
Electron Capture> 77.00%
Alpha Decay< 23.00%
Spontaneous Fission (suspected)No Data Available
Electron Capture (suspected)No Data Available
2471.2 secondsAlpha Decay99.90%
Spontaneous Fission< 0.10%
247m0.25 secondsAlpha Decay79.00%
Spontaneous Fission21.00%
24813 secondsAlpha Decay58.00%
Electron Capture42.00%
24921.7 secondsAlpha Decay> 60.00%
Electron Capture<= 40.00%
249m1.9 secondsAlpha Decay (suspected)No Data Available
25025 secondsAlpha Decay7.00%
Electron Capture93.00%
2514.3 minutesElectron Capture90.00%
Alpha Decay10.00%
2522.3 minutesElectron Capture<= 100.00%
2536 minutesElectron Capture<= 100.00%
Alpha DecayNo Data Available
25428 minutesElectron Capture<= 100.00%
Electron Capture<= 100.00%
25527 minutesElectron Capture92.00%
Alpha Decay8.00%
Spontaneous Fission< 0.15%
25677 minutesElectron Capture90.80%
Alpha Decay9.20%
Spontaneous Fission< 3.00%
2575.52 hoursElectron Capture85.00%
Alpha Decay15.00%
Spontaneous Fission< 1.00%
25851.5 daysAlpha Decay100.00%
Spontaneous FissionNo Data Available
258m57.0 minutesElectron Capture>= 70.00%
Spontaneous FissionNo Data Available
25996 minutesAlpha Decay< 1.30%
Spontaneous Fission100.00%
26031.8 daysSpontaneous Fission>= 42.00%
Alpha Decay<= 25.00%
Electron Capture<= 23.00%
Beta-minus Decay<= 10.00%
261No Data AvailableAlpha Decay (suspected)No Data Available
262No Data AvailableSpontaneous Fission (suspected)No Data Available
Alpha Decay (suspected)No Data Available