Thallium (Tl) — Element 81: Properties & Data | Aladdin Scientific
Thallium(Tl) — Element 81
Thallium (Tl) is a post-transition metal with atomic number 81 and atomic mass 204.383. It has melting point 577 K (304 °C), boiling point 1746 K (1473 °C), density 11.8 g/cm³. It sits in group 13 and period 6 of the periodic table and was discovered in 1861.
Key facts
| Atomic mass | 204.3830 u |
|---|---|
| Electron configuration | [Xe]6s2 4f14 5d10 6p1 |
| Oxidation states | +3, +1 |
| Electronegativity (Pauling) | 1.62 |
| Atomic radius (van der Waals) | 196 pm |
| Ionization energy | 6.108 eV |
| Electron affinity | 0.2 eV |
| Melting point | 577 K |
| Boiling point | 1746 K |
| Density | 11.8 g/cm³ |
| Standard state | Solid |
| Year discovered | 1861 |
Frequently asked questions
What is the electron configuration of thallium?
The ground-state electron configuration of thallium is [Xe]6s2 4f14 5d10 6p1.
What group and period is thallium in?
Thallium (Tl) is in group 13 and period 6 of the periodic table, classified as a post-transition metal.
What is the melting point of thallium?
Thallium melts at 577 K (304 °C).
What is the standard state of thallium?
Thallium is a solid at standard temperature and pressure.
Related elements
About this data: property values compiled from IUPAC Standard Atomic Weights (2021), the NIST Atomic Spectra Database, and PubChem. Curated by the Aladdin Scientific technical team. Last reviewed: .