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It's Elemental

Isotopes of the Element Cesium

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Cesium

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

Isotopes With A Known Natural Abundance

Mass NumberNatural AbundanceHalf-life
133100%STABLE

Known Isotopes

Mass NumberHalf-lifeDecay ModeBranching Percentage
1120.5 millisecondsProton Emission100.00%
11316.7 microsecondsProton Emission100.00%
Alpha DecayNo Data Available
1140.57 secondsElectron Capture99.98%
Electron Capture with
delayed Proton Emission
8.70%
Electron Capture with
delayed Alpha Decay
0.19%
Alpha Decay0.02%
1151.4 secondsElectron Capture100.00%
Electron Capture with
delayed Proton Emission
~ 0.07%
1160.70 secondsElectron Capture100.00%
Electron Capture with
delayed Proton Emission
2.80%
Electron Capture with
delayed Alpha Decay
0.05%
116m3.85 secondsElectron Capture100.00%
Electron Capture with
delayed Proton Emission
0.51%
Electron Capture with
delayed Alpha Decay
8.0×10-3 %
1178.4 secondsElectron Capture100.00%
117m6.5 secondsElectron CaptureNo Data Available
11814 secondsElectron Capture100.00%
Electron Capture with
delayed Proton Emission
< 0.04%
Electron Capture with
delayed Alpha Decay
< 2.4×10-3 %
118m17 secondsElectron Capture100.00%
Electron Capture with
delayed Proton Emission
< 0.04%
Electron Capture with
delayed Alpha Decay
< 2.4×10-3 %
11943.0 secondsElectron Capture100.00%
119m30.4 secondsElectron Capture100.00%
12061.3 secondsElectron Capture100.00%
Electron Capture with
delayed Alpha Decay
2.0×10-5 %
Electron Capture with
delayed Proton Emission
7.0×10-6 %
120m57 secondsElectron Capture100.00%
121155 secondsElectron Capture100.00%
121m122 secondsIsomeric Transition17.00%
Electron Capture83.00%
12221.18 secondsElectron Capture100.00%
122m0.36 secondsIsomeric Transition100.00%
122m13.70 minutesElectron Capture100.00%
1235.88 minutesElectron Capture100.00%
123m1.64 secondsIsomeric Transition100.00%
12430.9 secondsElectron Capture100.00%
124m6.3 secondsIsomeric Transition100.00%
12546.7 minutesElectron Capture100.00%
125m0.90 millisecondsIsomeric Transition100.00%
1261.64 minutesElectron Capture100.00%
1276.25 hoursElectron Capture100.00%
1283.66 minutesElectron Capture100.00%
12932.06 hoursElectron Capture100.00%
13029.21 minutesElectron Capture98.40%
Beta-minus Decay1.60%
130m3.46 minutesIsomeric Transition99.84%
Electron Capture0.16%
1319.689 daysElectron Capture100.00%
1326.480 daysElectron Capture98.13%
Beta-minus Decay1.87%
133STABLE--
1342.0652 yearsBeta-minus Decay100.00%
Electron Capture3.0×10-4 %
134m2.912 hoursIsomeric Transition100.00%
1352.3×10+6 yearsBeta-minus Decay100.00%
135m53 minutesIsomeric Transition100.00%
13613.04 daysBeta-minus Decay100.00%
136m17.5 secondsBeta-minus DecayNo Data Available
Isomeric Transition> 0.00%
13730.08 yearsBeta-minus Decay100.00%
13833.41 minutesBeta-minus Decay100.00%
138m2.91 minutesIsomeric Transition81.00%
Beta-minus Decay19.00%
1399.27 minutesBeta-minus Decay100.00%
14063.7 secondsBeta-minus Decay100.00%
14124.84 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
0.04%
1421.684 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
0.09%
1431.791 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
1.64%
1440.994 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
3.03%
144m< 1 secondsBeta-minus DecayNo Data Available
1450.587 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
14.70%
1460.321 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
14.20%
1470.230 secondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
28.50%
148146 millisecondsBeta-minus Decay100.00%
Beta-minus Decay with
delayed Neutron Emission
25.10%
149> 50 millisecondsBeta-minus DecayNo Data Available
Beta-minus Decay with
delayed Neutron Emission
No Data Available
150> 50 millisecondsBeta-minus DecayNo Data Available
Beta-minus Decay with
delayed Neutron Emission
No Data Available
151> 50 millisecondsBeta-minus DecayNo Data Available
Beta-minus Decay with
delayed Neutron Emission
No Data Available

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For questions about this page, please contact Carol McKisson.