Astatine

Halogen · 209.98715 u · group 17, period 6

Astatine · At

Atomic number85

SymbolAt

CategoryHalogen

Standard stateSolid

Group · Period · Block17 · 6 · p

Electron configuration[Xe]6s2 4f14 5d10 6p5

Atomic mass209.98715 u

Atomic radius202 pm

Protons / Neutrons / Electrons85 / 125 / 85

Shells (e⁻ per shell)2, 8, 18, 32, 18, 7

Electronegativity (Pauling)2.2

Ionization energy9.5 eV

Electron affinity2.8 eV

Oxidation states7, 5, 3, 1, -1

Melting point575 K · 301.9 °C

Boiling point—

Density7 g/cm³

Year discovered1940

CPK color

#754F45

State at room temp (25 °C)

solid

Position