| name | Thallium |
| latin | Thallium |
| french | Thallium |
| german | Thallium |
| symbol | Tl |
| proton number | 81 |
| atomic weight | 204.3833 |
| Pauling electronegativity | 1.62 |
| electronic configuration | [Xe] 4f145d106s26p1 1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p1 |
| melting point | 577 K, 304°C, 579°F |
| boiling point | 1746 K, 1473°C, 2683°F |
| group | 13 |
| period | 6 |
| state (by 20°C) | solid |
| oxidation states | +1, +3 |
| Year of discovery | Discoverer |
| 1861 | Sir William Crookes (1832-1919) |