Average atomic weight: 137.327(7) u
| Isotope | Fraction | Atomic weight/u |
| 130 | 0.00106(1) | 129.9063207(28) |
| 132 | 0.00101(1) | 131.9050611(11) |
| 134 | 0.02417(18) | 133.90450818(30) |
| 135 | 0.06592(12) | 134.90568838(29) |
| 136 | 0.07854(24) | 135.90457573(29) |
| 137 | 0.11232(24) | 136.90582714(30) |
| 138 | 0.71698(42) | 137.90524700(31) |
Atomic weights and isotopic compositions were obtained from NIST Database 144
The Atomic Line List does not contain any data for this element
(Atomic Line List v3.00b5)
