Most of the isotope data on this site has been obtained from the National Nuclear Data Center.
Naturally Occurring Isotopes
| Mass Number | Natural Abundance | Half-life |
| 136 | 0.185% | > 0.7×10+14 years |
| 138 | 0.251% | >= 0.9×10+14 years |
| 140 | 88.450% | STABLE |
| 142 | 11.114% | > 5×10+16 years |
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 119 | No Data Available | Electron Capture (suspected) | No Data Available |
| 120 | No Data Available | Electron Capture (suspected) | No Data Available |
| 121 | 1.1 seconds | Electron Capture | 100.00% |
| Electron Capture with delayed Proton Emission | ~ 1.00% | ||
| 122 | No Data Available | Electron Capture | No Data Available |
| Electron Capture with delayed Proton Emission | No Data Available | ||
| 123 | 3.8 seconds | Electron Capture | 100.00% |
| Electron Capture with delayed Proton Emission | > 0.00% | ||
| 124 | 6 seconds | Electron Capture | 100.00% |
| 125 | 9.7 seconds | Electron Capture | 100.00% |
| Electron Capture with delayed Proton Emission | No Data Available | ||
| 126 | 51.0 seconds | Electron Capture | 100.00% |
| 127 | 34 seconds | Electron Capture | 100.00% |
| 127m | 28.6 seconds | Electron Capture | 100.00% |
| 128 | 3.93 minutes | Electron Capture | 100.00% |
| 129 | 3.5 minutes | Electron Capture | > 0.00% |
| 130 | 22.9 minutes | Electron Capture | 100.00% |
| 131 | 10.3 minutes | Electron Capture | 100.00% |
| 131m | 5.4 minutes | Electron Capture | 100.00% |
| Isomeric Transition | No Data Available | ||
| 132 | 3.51 hours | Electron Capture | 100.00% |
| 132m | 9.4 milliseconds | Isomeric Transition | 100.00% |
| 133 | 97 minutes | Electron Capture | 100.00% |
| 133m | 5.1 hours | Electron Capture | No Data Available |
| Isomeric Transition | No Data Available | ||
| 134 | 3.16 days | Electron Capture | 100.00% |
| 135 | 17.7 hours | Electron Capture | 100.00% |
| 135m | 20 seconds | Isomeric Transition | 100.00% |
| 136 | > 0.7×10+14 years | Double Electron Capture | No Data Available |
| 137 | 9.0 hours | Electron Capture | 100.00% |
| 137m | 34.4 hours | Isomeric Transition | 99.21% |
| Electron Capture | 0.79% | ||
| 138 | >= 0.9×10+14 years | Double Electron Capture | 100.00% |
| 138m | 8.65 milliseconds | Isomeric Transition | 100.00% |
| 139 | 137.641 days | Electron Capture | 100.00% |
| 139m | 54.8 seconds | Isomeric Transition | 100.00% |
| 140 | STABLE | - | - |
| 141 | 32.508 days | Beta-minus Decay | 100.00% |
| 142 | > 5×10+16 years | Double Beta-minus Decay | No Data Available |
| 143 | 33.039 hours | Beta-minus Decay | 100.00% |
| 144 | 284.91 days | Beta-minus Decay | 100.00% |
| 145 | 3.01 minutes | Beta-minus Decay | 100.00% |
| 146 | 13.52 minutes | Beta-minus Decay | 100.00% |
| 147 | 56.4 seconds | Beta-minus Decay | 100.00% |
| 148 | 56 seconds | Beta-minus Decay | 100.00% |
| 149 | 5.3 seconds | Beta-minus Decay | 100.00% |
| 150 | 4.0 seconds | Beta-minus Decay | 100.00% |
| 151 | 1.76 seconds | Beta-minus Decay | 100.00% |
| 151m | 1.02 seconds | Beta-minus Decay | No Data Available |
| 152 | 1.4 seconds | Beta-minus Decay | 100.00% |
| 153 | > 100 nanoseconds | Beta-minus Decay (suspected) | No Data Available |
| 154 | > 100 nanoseconds | Beta-minus Decay | 100.00% |
| 155 | > 300 nanoseconds | Beta-minus Decay (suspected) | No Data Available |
| 156 | No Data Available | Beta-minus Decay (suspected) | No Data Available |
| 157 | No Data Available | Beta-minus Decay (suspected) | No Data Available |
This page is maintained by Steve Gagnon.