Most of the isotope data on this site has been obtained from the National Nuclear Data Center.
Naturally Occurring Isotopes
Protactinium has no naturally occurring isotopes.
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 212 | 5.1 milliseconds | Alpha Decay | 100.00% |
| 213 | 5.3 milliseconds | Alpha Decay | 100.00% |
| 214 | 17 milliseconds | Alpha Decay | <= 100.00% |
| 215 | 14 milliseconds | Alpha Decay | 100.00% |
| 216 | 0.15 seconds | Alpha Decay | ~ 98.00% |
| Electron Capture | ~ 2.00% | ||
| 217 | 3.6 milliseconds | Alpha Decay | 100.00% |
| 217m | 1.2 milliseconds | Alpha Decay | 73.00% |
| Isomeric Transition | 27.00% | ||
| 218 | 113 microseconds | Alpha Decay | 100.00% |
| 219 | 53 nanoseconds | Alpha Decay | 100.00% |
| 220 | 0.78 microseconds | Alpha Decay | 100.00% |
| Electron Capture | 3.0×10-7 % | ||
| 221 | 5.9 microseconds | Alpha Decay | 100.00% |
| 222 | 2.9 milliseconds | Alpha Decay | 100.00% |
| 223 | 5.1 milliseconds | Alpha Decay | 100.00% |
| 224 | 0.85 seconds | Alpha Decay | 100.00% |
| 225 | 1.7 seconds | Alpha Decay | 100.00% |
| 226 | 1.8 minutes | Alpha Decay | 74.00% |
| Electron Capture | 26.00% | ||
| 227 | 38.3 minutes | Alpha Decay | 85.00% |
| Electron Capture | 15.00% | ||
| 228 | 22.4 hours | Electron Capture | 98.15% |
| Alpha Decay | 1.85% | ||
| 229 | 1.50 days | Electron Capture | 99.52% |
| Alpha Decay | 0.48% | ||
| 230 | 17.4 days | Electron Capture | 92.20% |
| Beta-minus Decay | 7.80% | ||
| Alpha Decay | 3.2×10-3 % | ||
| 231 | 3.276×10+4 years | Alpha Decay | 100.00% |
| Spontaneous Fission | <= 2×10-11 % | ||
| 232 | 1.32 days | Beta-minus Decay | 100.00% |
| Electron Capture | No Data Available | ||
| 233 | 26.975 days | Beta-minus Decay | 100.00% |
| 234 | 6.70 hours | Beta-minus Decay | 100.00% |
| 234m | 1.159 minutes | Beta-minus Decay | 99.84% |
| Isomeric Transition | 0.16% | ||
| 235 | 24.44 minutes | Beta-minus Decay | 100.00% |
| 236 | 9.1 minutes | Beta-minus Decay | 100.00% |
| 237 | 8.7 minutes | Beta-minus Decay | 100.00% |
| 238 | 2.27 minutes | Beta-minus Decay | 100.00% |
| 239 | 1.8 hours | Beta-minus Decay | 100.00% |
| 240 | No Data Available | Beta-minus Decay (suspected) | No Data Available |
| 241 | No Data Available | No Data Available | No Data Available |
This page is maintained by Steve Gagnon.