(this element does not have any stable isotopes)
Atomic weight of the most stable isotope: 257.0951061(69) u
| Isotope | Atomic weight/u | Half-life |
| 247 | 247.07694(12) | 31 s 1 |
| 248 | 248.0771865(92) | 34.5 s 2 |
| 249 | 249.0789275(68) | 2.6 m 7 |
| 250 | 250.0795210(86) | 30 m 3 |
| 251 | 251.081540(16) | 5.30 h 8 |
| 252 | 252.0824671(61) | 25.39 h 4 |
| 253 | 253.0851846(37) | 3.00 d 12 |
| 254 | 254.0868544(30) | 3.240 h 2 |
| 255 | 255.0899640(52) | 20.07 h 7 |
| 256 | 256.0917745(78) | 157.6 m 13 |
| 257 | 257.0951061(69) | 100.5 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)
