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85At210.000
Astatine
MetalloidAstatine is a very rare radioactive chemical element with the chemical symbol At and atomic number 85. It occurs on Earth as the decay product of various heavier elements. All its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.
Phase: SolidAppearance: unknown, probably metallic
2, 8, 18, 32, 18, 7
Physical Properties
Atomic Mass210 u
Density6.35 g/cm³
Melting Point575 K
Boiling Point610 K
Period6
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p5
Semantic Config[Xe] 4f14 5d10 6s2 6p5
Shells2, 8, 18, 32, 18, 7
Electron Affinity233 kJ/mol
Electronegativity2.2
Ionization Energies
IE1: 899.003 kJ/mol
Discovery
Discovered byDale R. Corson