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 |
| 204 | 1.4% | >= 1.4×10+17 years |
| 206 | 24.1% | STABLE |
| 207 | 22.1% | STABLE |
| 208 | 52.4% | STABLE |
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 178 | 0.12 milliseconds | Alpha Decay | 100.00% |
| 179 | 3.5 milliseconds | Alpha Decay | 100.00% |
| 180 | 4.2 milliseconds | Alpha Decay | 100.00% |
| 181 | 36 milliseconds | Alpha Decay | 100.00% |
| 181m | 45 milliseconds | Alpha Decay | < 100.00% |
| 182 | 55 milliseconds | Electron Capture | ~ 2.00% |
| Alpha Decay | ~ 98.00% | ||
| 183 | 535 milliseconds | Alpha Decay | ~ 90.00% |
| 183m | 415 milliseconds | Alpha Decay | 100.00% |
| 184 | 490 milliseconds | Alpha Decay | 80.00% |
| Electron Capture | 20.00% | ||
| 185 | 6.3 seconds | Electron Capture | No Data Available |
| Alpha Decay | 34.00% | ||
| 185m | 4.3 seconds | Alpha Decay | 50.00% |
| Electron Capture | No Data Available | ||
| 186 | 4.82 seconds | Electron Capture | 60.00% |
| Alpha Decay | 40.00% | ||
| 187 | 18.3 seconds | Electron Capture | 88.00% |
| Alpha Decay | 12.00% | ||
| 187m | 15.2 seconds | Electron Capture | 90.50% |
| Alpha Decay | 9.50% | ||
| 188 | 25.1 seconds | Electron Capture | 90.70% |
| Alpha Decay | 9.30% | ||
| 189 | 39 seconds | Electron Capture | 100.00% |
| Alpha Decay | < 1.00% | ||
| 189m | 50 seconds | Electron Capture | 100.00% |
| Alpha Decay | < 1.00% | ||
| 190 | 71 seconds | Alpha Decay | 0.40% |
| Electron Capture | 99.60% | ||
| 191 | 1.33 minutes | Electron Capture | 99.99% |
| Alpha Decay | 0.01% | ||
| 191m | 2.18 minutes | Electron Capture | 100.00% |
| Alpha Decay | ~ 0.02% | ||
| 192 | 3.5 minutes | Electron Capture | 99.99% |
| Alpha Decay | 5.9×10-3 % | ||
| 193 | No Data Available | Electron Capture | No Data Available |
| 193m | 5.8 minutes | Electron Capture | 100.00% |
| 194 | 10.7 minutes | Alpha Decay | 7.3×10-6 % |
| Electron Capture | 100.00% | ||
| 195 | ≈ 15 minutes | Electron Capture | 100.00% |
| 195m | 15.0 minutes | Electron Capture | 100.00% |
| 196 | 37 minutes | Electron Capture | No Data Available |
| Alpha Decay | <= 3.0×10-5 % | ||
| 197 | 8.1 minutes | Electron Capture | 100.00% |
| 197m | 42.9 minutes | Electron Capture | 81.00% |
| Isomeric Transition | 19.00% | ||
| 198 | 2.4 hours | Electron Capture | 100.00% |
| 199 | 90 minutes | Electron Capture | 100.00% |
| 199m | 12.2 minutes | Electron Capture | ~ 7.00% |
| Isomeric Transition | ~ 93.00% | ||
| 200 | 21.5 hours | Electron Capture | 100.00% |
| 201 | 9.33 hours | Electron Capture | 100.00% |
| 201m | 60.8 seconds | Isomeric Transition | 100.00% |
| 202 | 52.5×10+3 years | Electron Capture | 100.00% |
| 202m | 3.54 hours | Isomeric Transition | 90.50% |
| Electron Capture | 9.50% | ||
| 203 | 51.92 hours | Electron Capture | 100.00% |
| 203m | 6.21 seconds | Isomeric Transition | 100.00% |
| 203m1 | 480 milliseconds | Isomeric Transition | 100.00% |
| 204 | >= 1.4×10+17 years | Alpha Decay | No Data Available |
| 204m | 66.93 minutes | Isomeric Transition | 100.00% |
| 205 | 1.73×10+7 years | Electron Capture | 100.00% |
| 205m | 5.55 milliseconds | Isomeric Transition | 100.00% |
| 206 | STABLE | - | - |
| 207 | STABLE | - | - |
| 207m | 0.806 seconds | Isomeric Transition | 100.00% |
| 208 | STABLE | - | - |
| 209 | 3.253 hours | Beta-minus Decay | 100.00% |
| 210 | 22.20 years | Beta-minus Decay | 100.00% |
| Alpha Decay | 1.9×10-6 % | ||
| 211 | 36.1 minutes | Beta-minus Decay | 100.00% |
| 212 | 10.64 hours | Beta-minus Decay | 100.00% |
| 213 | 10.2 minutes | Beta-minus Decay | 100.00% |
| 214 | 26.8 minutes | Beta-minus Decay | 100.00% |
| 215 | 147 seconds | Beta-minus Decay | No Data Available |
| 216 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 217 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 218 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 219 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 220 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
This page is maintained by Steve Gagnon.