Atoms of astatine (or astatine) are unstable and usually decay after a few hours into other atoms of lighter elements, such as bismuth. This radioactive element itself forms in a similar way when atoms of a heavier element called francium separate. Small amounts of this rare element are found in uranium ores, such as uraninite. Physicist Emilio Segrè was one of the first scientists to isolate a pure atom sample. He was able to do so using a particle accelerator.

Summary of properties (At)

Atomic weight[210]
Discoverer (year)Corson, Dale R. & Mackenzie, K. R. (1940)
Natural formnon-metal solid (-)
Electron configuration[Xe] 414 5d10 6s2 6p5
Melting point (ºC)302
Boiling point (ºC)337
Abundance in earth's crust (ppm)<0.001
Isotope (abundance)
Density g/cm3
Van der Waals radius (pm)202
Covalent radius (pm)148
Electronegativity (Pauling)2.2
Vaporization enthalpy (kJ/mol)-
Enthalpy of fusion (kJ/mol)-
Specific heat capacity (J/g·K) at 25ºC and 1 atm-
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.020
Oxidation state
Electron affinity (eV)2.80
1st Ionization potential (eV)

Back to the Periodic Table of the Elements.