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 |
| 120 | 0.09% | STABLE |
| 122 | 2.55% | STABLE |
| 123 | 0.89% | > 9.2×10+16 years |
| 124 | 4.74% | STABLE |
| 125 | 7.07% | STABLE |
| 126 | 18.84% | STABLE |
| 128 | 31.74% | 2.41×10+24 years |
| 130 | 34.08% | >= 3.0×10+24 years |
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 105 | 0.62 microseconds | Alpha Decay | 100.00% |
| 106 | 70 microseconds | Alpha Decay | 100.00% |
| 107 | 3.1 milliseconds | Alpha Decay | 70.00% |
| Electron Capture | 30.00% | ||
| 108 | 2.1 seconds | Alpha Decay | 49.00% |
| Electron Capture with delayed Proton Emission | 2.40% | ||
| Electron Capture | 51.00% | ||
| 109 | 4.6 seconds | Electron Capture | 96.10% |
| Electron Capture with delayed Proton Emission | 9.40% | ||
| Alpha Decay | 3.90% | ||
| Electron Capture with delayed Alpha Decay | < 5.0×10-3 % | ||
| 110 | 18.6 seconds | Electron Capture | 100.00% |
| Alpha Decay | ~ 3.0×10-3 % | ||
| 111 | 19.3 seconds | Electron Capture | 100.00% |
| Electron Capture with delayed Proton Emission | No Data Available | ||
| 112 | 2.0 minutes | Electron Capture | 100.00% |
| 113 | 1.7 minutes | Electron Capture | 100.00% |
| 114 | 15.2 minutes | Electron Capture | 100.00% |
| 115 | 5.8 minutes | Electron Capture | 100.00% |
| 115m | 6.7 minutes | Electron Capture | <= 100.00% |
| Isomeric Transition | No Data Available | ||
| 116 | 2.49 hours | Electron Capture | 100.00% |
| 117 | 62 minutes | Electron Capture | 100.00% |
| 117m | 103 milliseconds | Isomeric Transition | 100.00% |
| 118 | 6.00 days | Electron Capture | 100.00% |
| 119 | 16.05 hours | Electron Capture | 100.00% |
| 119m | 4.70 days | Electron Capture | 100.00% |
| Isomeric Transition | < 8.0×10-3 % | ||
| 120 | STABLE | - | - |
| 121 | 19.17 days | Electron Capture | 100.00% |
| 121m | 164.2 days | Isomeric Transition | 88.60% |
| Electron Capture | 11.40% | ||
| 122 | STABLE | - | - |
| 123 | > 9.2×10+16 years | Electron Capture | 100.00% |
| 123m | 119.2 days | Isomeric Transition | 100.00% |
| 124 | STABLE | - | - |
| 125 | STABLE | - | - |
| 125m | 57.40 days | Isomeric Transition | 100.00% |
| 126 | STABLE | - | - |
| 127 | 9.35 hours | Beta-minus Decay | 100.00% |
| 127m | 106.1 days | Isomeric Transition | 97.60% |
| Beta-minus Decay | 2.40% | ||
| 128 | 2.41×10+24 years | Double Beta-minus Decay | 100.00% |
| 129 | 69.6 minutes | Beta-minus Decay | 100.00% |
| 129m | 33.6 days | Isomeric Transition | 63.00% |
| Beta-minus Decay | 37.00% | ||
| 130 | >= 3.0×10+24 years | Double Beta-minus Decay | 100.00% |
| 131 | 25.0 minutes | Beta-minus Decay | 100.00% |
| 131m | 33.25 hours | Beta-minus Decay | 74.10% |
| Isomeric Transition | 25.90% | ||
| 131m1 | 93 milliseconds | Isomeric Transition | 100.00% |
| 132 | 3.204 days | Beta-minus Decay | 100.00% |
| 133 | 12.5 minutes | Beta-minus Decay | 100.00% |
| 133m | 55.4 minutes | Beta-minus Decay | 83.50% |
| Isomeric Transition | 16.50% | ||
| 134 | 41.8 minutes | Beta-minus Decay | 100.00% |
| 135 | 19.0 seconds | Beta-minus Decay | 100.00% |
| 136 | 17.63 seconds | Beta-minus Decay with delayed Neutron Emission | 1.31% |
| Beta-minus Decay | 100.00% | ||
| 137 | 2.49 seconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 2.99% | ||
| 138 | 1.4 seconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 6.30% | ||
| 139 | > 150 nanoseconds | Beta-minus Decay | No Data Available |
| Beta-minus Decay with delayed Neutron Emission | No Data Available | ||
| 140 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| Beta-minus Decay with delayed Neutron Emission | No Data Available | ||
| 141 | > 150 nanoseconds | Beta-minus Decay (suspected) | No Data Available |
| 141m | 150 nanoseconds | Beta-minus Decay with delayed Neutron Emission (suspected) | No Data Available |
| 142 | No Data Available | No Data Available | No Data Available |
| 143 | > 408 nanoseconds | Beta-minus Decay | No Data Available |
| Beta-minus Decay with delayed Neutron Emission | No Data Available | ||
| Beta-minus Decay with delayed Double Neutron Emission | No Data Available |
This page is maintained by Steve Gagnon.