Astatine

Atomic number

85

Atomic mass (u)

209.98715

Category

Halogen

Standard state

Solid

Melting point

301.85 °C (575 K)

Boiling point

Not reported

Density (g/cm³)

7

Electronegativity (Pauling)

2.2

Electron configuration

[Xe]6s2 4f14 5d10 6p5

Oxidation states

7, 5, 3, 1, -1

Atomic radius (pm)

202

First ionization energy (eV)

9.5

Discovery & recognition

Discovery year / period (PubChem)

1940

Discovery credited to (RSC)

Dale R. Corson, Kenneth Ross MacKenzie, Emilio Segrè

Date or period recorded by RSC

1940

Discovery place

Not supplied in the structured record; see the RSC history source.

An ancient date does not identify a first human discovery. Different references may date observation, isolation and formal recognition differently.

Natural occurrence & production

The creation of an element’s nuclei and its concentration into terrestrial deposits are different processes. The occurrence note below concerns its presence or production on Earth; it is not a complete account of nucleosynthesis.

“Astatine can be obtained in a variety of ways, but not in weighable amounts.”

Royal Society of Chemistry · occurrence excerpt ↗

Continue the research

Reference values are not product specifications. Blank values have not been estimated. For superheavy elements, some properties and family assignments are theoretical or incompletely measured.