Astatine

Symbol | At
Latin name | Astatum
Atomic number | 85
Period | 6
Element category | Halogens
Relative atomic mass | 209.9871
Group | VII.A
Electronegativity | 2.2
Oxidation numbers | -1, 1, 3, 5, 7
State | Solid
Melting point [°C] | 302
Boiling point [°C] | 330
Atomic radius [pm] | 127
Thermal conductivity [W m-1K-1] | 1.7
Discovery | 1940
1.st ionization energy [eV] | 9.5
Stable isotopes | 0
Unstable isotopes | 21