Most of the isotope data on this site has been obtained from the National Nuclear Data Center.
Naturally Occurring Isotopes
Radon has no naturally occurring isotopes.
Known Isotopes
| Mass Number | Half-life | Decay Mode | Branching Percentage |
| 193 | 1.15 milliseconds | Alpha Decay | 100.00% |
| 194 | 0.78 milliseconds | Alpha Decay | 100.00% |
| 195 | 6 milliseconds | Alpha Decay | 100.00% |
| 195m | 5 milliseconds | Alpha Decay | 100.00% |
| 196 | 4.4 milliseconds | Alpha Decay | 99.90% |
| Electron Capture | ~ 0.10% | ||
| 197 | 53 milliseconds | Alpha Decay | 100.00% |
| 197m | 25 milliseconds | Alpha Decay | 100.00% |
| 198 | 65 milliseconds | Alpha Decay | No Data Available |
| Electron Capture | No Data Available | ||
| 199 | 0.59 seconds | Alpha Decay | 94.00% |
| Electron Capture | 6.00% | ||
| 199m | 0.31 seconds | Alpha Decay | 97.00% |
| Electron Capture | 3.00% | ||
| 200 | 1.03 seconds | Alpha Decay | 86.00% |
| Electron Capture | 14.00% | ||
| 201 | 7.0 seconds | Alpha Decay | No Data Available |
| Electron Capture | No Data Available | ||
| 201m | 3.8 seconds | Electron Capture | No Data Available |
| Alpha Decay | No Data Available | ||
| 202 | 9.7 seconds | Alpha Decay | 78.00% |
| Electron Capture | 22.00% | ||
| 203 | 44 seconds | Alpha Decay | 66.00% |
| Electron Capture | 34.00% | ||
| 203m | 26.9 seconds | Alpha Decay | 75.00% |
| Electron Capture | 25.00% | ||
| 204 | 74.5 seconds | Alpha Decay | 72.40% |
| Electron Capture | 27.60% | ||
| 205 | 170 seconds | Alpha Decay | 24.60% |
| Electron Capture | 75.40% | ||
| 206 | 5.67 minutes | Alpha Decay | 62.00% |
| Electron Capture | 38.00% | ||
| 207 | 9.25 minutes | Electron Capture | 79.00% |
| Alpha Decay | 21.00% | ||
| 208 | 24.35 minutes | Alpha Decay | 62.00% |
| Electron Capture | 38.00% | ||
| 209 | 28.5 minutes | Electron Capture | 83.00% |
| Alpha Decay | 17.00% | ||
| 210 | 2.4 hours | Electron Capture | 4.00% |
| Alpha Decay | 96.00% | ||
| 211 | 14.6 hours | Electron Capture | 72.60% |
| Alpha Decay | 27.40% | ||
| 212 | 23.9 minutes | Alpha Decay | 100.00% |
| 213 | 19.5 milliseconds | Alpha Decay | 100.00% |
| 214 | 0.27 microseconds | Alpha Decay | 100.00% |
| 215 | 2.30 microseconds | Alpha Decay | 100.00% |
| 216 | 45 microseconds | Alpha Decay | 100.00% |
| 217 | 0.54 milliseconds | Alpha Decay | 100.00% |
| 218 | 35 milliseconds | Alpha Decay | 100.00% |
| 219 | 3.96 seconds | Alpha Decay | 100.00% |
| 220 | 55.6 seconds | Alpha Decay | 100.00% |
| 221 | 25 minutes | Beta-minus Decay | 78.00% |
| Alpha Decay | 22.00% | ||
| 222 | 3.8235 days | Alpha Decay | 100.00% |
| 223 | 24.3 minutes | Beta-minus Decay | 100.00% |
| 224 | 107 minutes | Beta-minus Decay | 100.00% |
| 225 | 4.66 minutes | Beta-minus Decay | 100.00% |
| 226 | 7.4 minutes | Beta-minus Decay | 100.00% |
| 227 | 20.8 seconds | Beta-minus Decay | 100.00% |
| 228 | 65 seconds | Beta-minus Decay | 100.00% |
| 229 | 12.0 seconds | Beta-minus Decay | 100.00% |
| 230 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
| 231 | > 300 nanoseconds | Beta-minus Decay | No Data Available |
This page is maintained by Steve Gagnon.