81 Tl

Thallium

Post-transition metal
Atomic number81
CategoryPost-transition metal
Atomic mass204.38
Electron configuration[Xe]4f¹⁴ 5d¹⁰ 6s² 6p¹
Oxidation states+1, +3
Electronegativity1.62
Melting point304 °C
Boiling point1,473 °C
Density11.85 g/cm³
Crystal structureClose-packed hexagonal
Group13
Period6
Blockp
Discovered1,861
Crustal abundance0.85 ppm

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