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81
Tl
204.38
Thallium
Post-transition metals · Group 13 · Period 6
Atomic properties
| Atomic number | 81 |
|---|---|
| Symbol | Tl |
| Standard atomic weight | 204.38 |
| Classification | Post-transition metals |
| Group | 13 |
| Period | 6 |
| Block | p-block |
| Electron configuration | [Xe] 4f14 5d10 6s2 6p1 |
| Electronegativity (Pauling) | 1.62 |
| Common oxidation states | +3, +1 |
Physical properties
| Phase at 20 °C | Solid |
|---|---|
| Density | 11.85 g/cm³ |
| Melting point | 304 °C |
| Boiling point | 1473 °C |
| Discovered | 1861 |
| CAS number | — |