Astatine | At2 - PubChem
pubchem.ncbi.nlm.nih.gov › compound › astatine2004-09-16. Diastatine is an elemental astatine. Astatine. A radioactive halogen with the atomic symbol At, and atomic number 85. Its isotopes range in mass number from 200 to 219 and all have an extremely short half-life. Astatine may be of use in the treatment of hyperthyroidism because it emits ALPHA PARTICLES.
Astatine - Wikipedia
en.wikipedia.org › wiki › AstatineAstatine. Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.