Periodic table / Other metals
81Thallium
Thallium is an other metal in group 13, period 6. At 25 °C it is a solid.
- Symbol
- Tl
- Atomic number
- 81 protons in the nucleus
- Standard atomic weight
- 204.38 ± 0.01
- Electron configuration
- [Xe] 4f14 5d10 6s2 6p1
- Electrons in each shell
- 2, 8, 18, 32, 18, 3
- Group, period, block
- 13, 6, p
- Family
- Other metals
- State at 25 °C
- solid
- Electronegativity
- 1.62 (Pauling scale)
- First ionisation energy
- 589.4 kJ/mol (6.1082873 eV)
Where these numbers come from
Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.