Name Astatine
Symbol At
Atomic Number 85
Atomic Mass 210.0 atomic mass units
Number of Protons 85
Number of Neutrons 125
Number of Electrons 85
Melting Point 302.0° C
Boiling Point 337.0° C
Density No data
Normal Phase Solid
Family Halogens
Period 6
Cost Unavailable



Origin of Name From the Greek word astatos, meaning unstable
Date and Place of Discovery At the University of California in 1940
Discovered by Dale R. Corson, K. R. MacKenzie, Emilio Segrè
Common Compounds
  • No known compounds
Interesting facts
  • There is less than one ounce of astatine in the entire earth's crust and exists as a result of uranium and thorium decay.
  • Because it is scarce, it is mostly produced by bombarding bismuth with alpha particles.
  • Only about .05 micrograms of astatine have been produced so far.
  • It was synthesized by Corson, MacKenzie and Segrè by bombarding bismuth with alpha particles.
  • It is highly reactive.
  • It behaves like other halogens, especially like iodine and may accumulate in the human thyroid gland.
  • It is more metallic than iodine.
Common Uses
  • There are no known uses for astatine.


Photo Courtesy of
Mr. Tree's House of Science
Chemical Elements
Jefferson Labs
Mrs. Purdy's Web Page
Web Elements

Astatine Atomic Structure Elements by Name Elements by Number