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 |
| 121 | 57.21% | STABLE |
| 123 | 42.79% | STABLE |
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 103 | 1.5 microseconds | Electron Capture (suspected) | No Data Available |
| 104 | 0.44 seconds | Electron Capture | 100.00% |
| Electron Capture with delayed Proton Emission | < 7.00% | ||
| Proton Emission | < 1.00% | ||
| 105 | 1.22 seconds | Electron Capture | 99.00% |
| Proton Emission | 1.00% | ||
| 106 | 0.6 seconds | Electron Capture | No Data Available |
| 107 | 4.0 seconds | Electron Capture | 100.00% |
| 108 | 7.4 seconds | Electron Capture | 100.00% |
| 109 | 17.0 seconds | Electron Capture | 100.00% |
| 110 | 23.0 seconds | Electron Capture | 100.00% |
| 111 | 75 seconds | Electron Capture | 100.00% |
| 112 | 51.4 seconds | Electron Capture | 100.00% |
| 113 | 6.67 minutes | Electron Capture | 100.00% |
| 114 | 3.49 minutes | Electron Capture | 100.00% |
| 115 | 32.1 minutes | Electron Capture | 100.00% |
| 116 | 15.8 minutes | Electron Capture | 100.00% |
| 116m | 60.3 minutes | Electron Capture | 100.00% |
| 117 | 2.80 hours | Electron Capture | 100.00% |
| 118 | 3.6 minutes | Electron Capture | 100.00% |
| 118m | 5.00 hours | Electron Capture | 100.00% |
| 119 | 38.19 hours | Electron Capture | 100.00% |
| 119m | 0.85 seconds | Isomeric Transition | 100.00% |
| 120 | 15.89 minutes | Electron Capture | 100.00% |
| 120m | 5.76 days | Electron Capture | 100.00% |
| 121 | STABLE | - | - |
| 122 | 2.7238 days | Beta-minus Decay | 97.59% |
| Electron Capture | 2.41% | ||
| 122m | 4.191 minutes | Isomeric Transition | 100.00% |
| 123 | STABLE | - | - |
| 124 | 60.20 days | Beta-minus Decay | 100.00% |
| 124m | 93 seconds | Isomeric Transition | 75.00% |
| Beta-minus Decay | 25.00% | ||
| 124m1 | 20.2 minutes | Isomeric Transition | 100.00% |
| 125 | 2.75856 years | Beta-minus Decay | 100.00% |
| 126 | 12.35 days | Beta-minus Decay | 100.00% |
| 126m | 19.15 minutes | Beta-minus Decay | 86.00% |
| Isomeric Transition | 14.00% | ||
| 126m1 | ≈ 11 seconds | Isomeric Transition | 100.00% |
| 127 | 3.85 days | Beta-minus Decay | 100.00% |
| 128 | 9.01 hours | Beta-minus Decay | 100.00% |
| 128m | 10.4 minutes | Beta-minus Decay | 96.40% |
| Isomeric Transition | 3.60% | ||
| 129 | 4.40 hours | Beta-minus Decay | 100.00% |
| 129m | 17.7 minutes | Beta-minus Decay | 85.00% |
| Isomeric Transition | 15.00% | ||
| 130 | 39.5 minutes | Beta-minus Decay | 100.00% |
| 130m | 6.3 minutes | Beta-minus Decay | 100.00% |
| 131 | 23.03 minutes | Beta-minus Decay | 100.00% |
| 132 | 2.79 minutes | Beta-minus Decay | 100.00% |
| 132m | 4.10 minutes | Beta-minus Decay | 100.00% |
| 133 | 2.34 minutes | Beta-minus Decay | 100.00% |
| 134 | 0.78 seconds | Beta-minus Decay | 100.00% |
| 134m | 10.07 seconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 0.09% | ||
| 135 | 1.679 seconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 22.00% | ||
| 136 | 0.923 seconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 16.30% | ||
| 137 | 492 milliseconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 49.00% | ||
| 138 | 350 milliseconds | Beta-minus Decay with delayed Neutron Emission | 72.00% |
| Beta-minus Decay | 100.00% | ||
| 139 | 93 milliseconds | Beta-minus Decay | 100.00% |
| Beta-minus Decay with delayed Neutron Emission | 90.00% | ||
| 140 | > 407 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.