Astatine

Document v1 · published by Koskamo · updated 2026-10-04

Astatine (At) is chemical element 85, a halogen in group 17, period 6 (PubChem).

Atomic number: 85
Symbol: At
Group: 17
Period: 6
Atomic mass: 209.98715 u
Electron configuration: [Xe]6s2 4f14 5d10 6p5
Electronegativity (Pauling scale): 2.2
Atomic radius (van der Waals): 202 pm
Ionization energy: 9.5 eV
Electron affinity: 2.8 eV
Oxidation states: 7, 5, 3, 1, -1
Standard state: Solid
Melting point: 575 K
Density: 7 g/cm³
Chemical group: Halogen
Year discovered: 1940

Source and provenance

Original source: pubchem.ncbi.nlm.nih.gov
Published on Koskamo by: Koskamo
Citation version: Document v1
Reuse: PubChem periodic table data (NIH/NLM, pubchem.ncbi.nlm.nih.gov/ptable); group and period from Jefferson Lab via PubChem

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Version history

Published by Koskamo2026-10-04
Version 1