(this element does not have any stable isotopes)
Atomic weight of the most stable isotope: 208.9824308(20) u
| Isotope | Atomic weight/u | Half-life |
| 204 | 203.980310(12) | 3.519 h 12 |
| 205 | 204.981203(22) | 1.74 h 8 |
| 206 | 205.9804740(43) | 8.8 d 1 |
| 207 | 206.9815938(72) | 5.80 h 2 |
| 208 | 207.9812461(19) | 2.898 y 2 |
| 209 | 208.9824308(20) | 124 y 3 |
| 210 | 209.9828741(13) | 138.376 d 2 |
Units: y = year, d = day, h = hour, m = minute, s = second, ms = millisecond, µs = microsecond.
Numbers in italics are uncertainties with the same unit as the last digit of the half-life.
Atomic weights were obtained from NIST Database 144
The half-life of radioactive isotopes was obtained from the Nuclear Wallet Cards
The Atomic Line List does not contain any data for this element
(Atomic Line List v3.00b5)
