Average atomic weight: 121.760(1) u
| Isotope | Fraction | Atomic weight/u |
| 121 | 0.5721(5) | 120.9038120(30) |
| 123 | 0.4279(5) | 122.9042132(23) |
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)
