Most of the isotope data on this site has been obtained from the National Nuclear Data Center.
Naturally Occurring Isotopes
Polonium has no naturally occurring isotopes.
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 186 | No Data Available | No Data Available | No Data Available |
| 187 | 1.40 milliseconds | Alpha Decay | 100.00% |
| 188 | 0.275 milliseconds | Electron Capture | 100.00% |
| Alpha Decay | No Data Available | ||
| 189 | 3.5 milliseconds | Alpha Decay | 100.00% |
| 190 | 2.46 milliseconds | Alpha Decay | 100.00% |
| 191 | 22 milliseconds | Alpha Decay | 99.00% |
| 191m | 93 milliseconds | Alpha Decay | 96.00% |
| 192 | 32.2 milliseconds | Alpha Decay | ~ 99.50% |
| Electron Capture | ~ 0.50% | ||
| 193 | 245 milliseconds | Alpha Decay | <= 100.00% |
| 193m | 370 milliseconds | Alpha Decay | <= 100.00% |
| 194 | 0.392 seconds | Alpha Decay | 100.00% |
| Electron Capture | No Data Available | ||
| 195 | 4.64 seconds | Alpha Decay | 75.00% |
| Electron Capture | 25.00% | ||
| 195m | 1.92 seconds | Electron Capture | ~ 10.00% |
| Isomeric Transition | < 0.01% | ||
| Alpha Decay | ~ 90.00% | ||
| 196 | 5.8 seconds | Alpha Decay | ~ 98.00% |
| Electron Capture | ~ 2.00% | ||
| 197 | 84 seconds | Electron Capture | 56.00% |
| Alpha Decay | 44.00% | ||
| 197m | 32 seconds | Alpha Decay | 84.00% |
| Electron Capture | 16.00% | ||
| Isomeric Transition | 0.01% | ||
| 198 | 1.77 minutes | Alpha Decay | 57.00% |
| Electron Capture | 43.00% | ||
| 199 | 5.47 minutes | Electron Capture | 92.50% |
| Alpha Decay | 7.50% | ||
| 199m | 4.17 minutes | Electron Capture | 73.50% |
| Alpha Decay | 24.00% | ||
| Isomeric Transition | 2.50% | ||
| 200 | 11.51 minutes | Electron Capture | 88.90% |
| Alpha Decay | 11.10% | ||
| 201 | 15.6 minutes | Electron Capture | 98.87% |
| Alpha Decay | 1.13% | ||
| 201m | 8.96 minutes | Electron Capture | 41.40% |
| Alpha Decay | 2.40% | ||
| Isomeric Transition | 56.20% | ||
| 202 | 44.6 minutes | Electron Capture | 98.08% |
| Alpha Decay | 1.92% | ||
| 203 | 36.7 minutes | Electron Capture | 99.89% |
| Alpha Decay | 0.11% | ||
| 203m | 45 seconds | Isomeric Transition | 100.00% |
| Electron Capture | No Data Available | ||
| 204 | 3.519 hours | Electron Capture | 99.33% |
| Alpha Decay | 0.67% | ||
| 205 | 1.74 hours | Alpha Decay | 0.04% |
| Electron Capture | 99.96% | ||
| 205m | 0.645 milliseconds | Isomeric Transition | 100.00% |
| 205m1 | 57.4 milliseconds | Isomeric Transition | 100.00% |
| 206 | 8.8 days | Electron Capture | 94.55% |
| Alpha Decay | 5.45% | ||
| 207 | 5.80 hours | Electron Capture | 99.98% |
| Alpha Decay | 0.02% | ||
| 207m | 2.79 seconds | Isomeric Transition | 100.00% |
| 208 | 2.898 years | Alpha Decay | 100.00% |
| Electron Capture | 4.0×10-3 % | ||
| 209 | 102 years | Electron Capture | 0.48% |
| Alpha Decay | 99.52% | ||
| 210 | 138.376 days | Alpha Decay | 100.00% |
| 211 | 0.516 seconds | Alpha Decay | 100.00% |
| 211m | 25.2 seconds | Alpha Decay | 99.98% |
| Isomeric Transition | 0.02% | ||
| 212 | 0.299 microseconds | Alpha Decay | 100.00% |
| 212m | 45.1 seconds | Alpha Decay | 99.93% |
| Isomeric Transition | 0.07% | ||
| 213 | 3.72 microseconds | Alpha Decay | 100.00% |
| 214 | 164.3 microseconds | Alpha Decay | 100.00% |
| 215 | 1.781 milliseconds | Alpha Decay | 100.00% |
| Beta-minus Decay | 2.3×10-4 % | ||
| 216 | 0.145 seconds | Alpha Decay | 100.00% |
| 217 | 1.53 seconds | Alpha Decay | No Data Available |
| 218 | 3.098 minutes | Alpha Decay | 99.98% |
| Beta-minus Decay | 0.02% | ||
| 219 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 220 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 221 | 112 seconds | Beta-minus Decay (suspected) | No Data Available |
| 222 | 550 seconds | Beta-minus Decay (suspected) | No Data Available |
| 223 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 224 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 225 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 226 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 227 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
This page is maintained by Steve Gagnon.