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Thallium

Document v1 · published by Koskamo · updated 2026-10-04

Original source

Thallium (Tl) is chemical element 81, a post-transition metal in group 13, period 6 (PubChem).

  • Atomic number: 81
  • Symbol: Tl
  • Group: 13
  • Period: 6
  • Atomic mass: 204.383 u
  • Electron configuration: [Xe]6s2 4f14 5d10 6p1
  • Electronegativity (Pauling scale): 1.62
  • Atomic radius (van der Waals): 196 pm
  • Ionization energy: 6.108 eV
  • Electron affinity: 0.2 eV
  • Oxidation states: +3, +1
  • Standard state: Solid
  • Melting point: 577 K
  • Boiling point: 1746 K
  • Density: 11.8 g/cm³
  • Chemical group: Post-transition metal
  • Year discovered: 1861

Source and provenance

Original source
pubchem.ncbi.nlm.nih.gov
Published on Koskamo by
Koskamo
Citation version
Document v1
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PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

  1. Published by Koskamo

    Version 1