| Quantity | Value | Units | Value | Units |
| Atomic number | 81 | |||
| Atomic mass | 204.38(2) | g mole-1 | ||
| Specific gravity | 11.72 | g cm-3 | ||
| Mean excitation energy | 810.0 | eV | ||
| Minimum ionization | 1.125 | MeV g-1cm2 | 13.19 | MeV cm-1 |
| Nuclear collision length | 113.6 | g cm-2 | 9.696 | cm |
| Nuclear interaction length | 198.7 | g cm-2 | 16.96 | cm |
| Pion collision length | 136.9 | g cm-2 | 11.68 | cm |
| Pion interaction length | 225.3 | g cm-2 | 19.22 | cm |
| Radiation length | 6.42 | g cm-2 | 0.5477 | cm |
| Critical energy | 7.50 | MeV (for e-) | 7.23 | MeV (for e+) |
| Molière radius | 18.15 | g cm-2 | 1.549 | cm |
| Plasma energy ℏωp | 62.10 | eV | ||
| Muon critical energy | 142. | GeV |