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Thallium (Tl)

Thallium (Tl) is element 81 of the periodic table, a post-transition metal in period 6 and group 13. Its standard atomic weight is 204.38, so one mole of thallium atoms has a mass of 204.38 g. At room temperature it is a solid; it melts at 303.85 °C and boils at 1472.85 °C.

81 Tl Thallium 204.38

Period 6, group 13 · Post-transition metal

← Hg Mercury Pb Lead →

Atomic number	81
Symbol	Tl
Standard atomic weight	204.38
Molar mass	204.38 g/mol
Category	Post-transition metal
Group	13
Period	6
Block	p-block
Electron configuration	[Xe] 6s² 4f¹⁴ 5d¹⁰ 6p¹
Oxidation states	+3, +1
Electronegativity (Pauling)	1.62
Atomic radius (van der Waals)	196 pm
First ionisation energy	6.108 eV (589.3 kJ/mol)
Electron affinity	0.2 eV
State at room temperature	Solid
Melting point	577 K (303.85 °C)
Boiling point	1746 K (1472.85 °C)
Density	11.8 g/cm³
Discovered	1861

Group 13

B · Boron Al · Aluminium Ga · Gallium In · Indium Nh · Nihonium

Calculate with Thallium

Molar mass of Tl Balance an equation Grams, moles and particles Whole periodic table

Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.