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Astronomy Chemical element

Thallium

Thallium (Tl) is a chemical element belonging to the category Post-transition metal, with atomic number 81 and atomic mass 204.3800 u. This sheet describes its fundamental properties, periodic position and physical characteristics.

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Astronomy · Chemical element

Thallium

EL29

Identity

  • Name: Thallium
  • Symbol: Tl
  • Atomic number: 81
  • Atomic mass: 204.3800 u

Position in the periodic table

  • Group: 13
  • Period: 6
  • Category: Post-transition metal

Physico-chemical properties

  • Standard state: Solid
  • Melting point: About 304°C
  • Density (at 20°C): 11.8 g/cm³
  • Electron configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹

Scientific description

Thallium is a chemical element with symbol Tl and atomic number 81. It belongs to the category of Post-transition metal and occupies group 13 and period 6. Its standard atomic mass is 204.3800 u.