Properties of Thallium (Tl)
Thallium is a chemical element with the symbol (Tl) and atomic number 81. It is a soft, bluish-gray metal that belongs to the group of elements known as the post-transition metals. Thallium is relatively rare in the Earth’s crust and has limited commercial applications.
The following table provides a comprehensive list of thallium (Tl) properties in both SI and US customary/Imperial units at normal temperature and pressure (NTP).
Click on the button to switch between Metric and Imperial units.
| Physical Properties | Metric |
|---|---|
| Crystal Structure | Hexagonal close-packed (hcp) |
| Atomic Number | 81 |
| Molar Mass | 204.3833 g/mol |
| Density | 11850 kg/m3 |
| Mechanical Properties | Metric |
| Young’s Modulus (E) | 7.9 GPa |
| Shear Modulus (G) | 2.7 GPa |
| Bulk Modulus (K) | 28.5 GPa |
| Poisson’s Ratio (ν) | 0.45 |
| Mohs Hardness | 1.2 |
| Thermal Properties | Metric |
| Melting Point | 304 °C |
| Boiling Point | 1473 °C |
| Thermal Conductivity (27°C) | 46.1 W/m·K |
| Specific Heat Capacity (Cp) (25°C) | 130 J/kg·K |
| Coefficient of Thermal Expansion (αL) (25°C) | 2.99×10-5 1/°C |
| Electrical Properties | Metric |
| Electrical Resistivity | 1.8×10-5 Ω·cm |
Unless stated otherwise, all values are taken at room temperature (approximately 20°C or 68°F) and 1 atm pressure. (1 atm = 101,325 Pa)
References: 1) Cardarelli, François. Materials Handbook: A Concise Desktop Reference. Switzerland: Springer International Publishing, 2018. 2) CRC Handbook of Chemistry and Physics, 97th Edition. United Kingdom: CRC Press, 2016-2017. 3) A.M. Howatson, P.G. Lun, J.D. Todd, P.D. Engineering Tables and Data. United Kingdom: University of Oxford, Department of Engineering Science, 2009.