noun. A highly unstable radioactive element, the heaviest of the halogen group, that resembles iodine in solution. Its longest lived isotope has a mass number of 210 and has a half-life of 8.3 hours. Atomic number 85; melting point 302°C; boiling point 337°C; valence probably 1, 3, 5, 7. cross-reference: Periodic Table.

noun. A highly radioactive chemical element (symbol At), one of the halogens, with atomic number 85.

noun. a highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium

"In collaboration with Traude Cless-Bernert, she discovered the natural occurrence of isotopes of astatine by observation of their radioactive alpha particle decays."

astatane  eka-astatine  

chemical element  element  halogen