ASTATO

The astato is a chemical artificial element of the periodic table which symbol is At and his atomic number is 85. This radioactive element is most weighed of the halogens and takes place from the degradation of uranium and torio.
Alpha is created by bombardment of bismuth by particles.
The ástato (of the Greek astat??, astatos, that it means unstably) it was obtained by the first time in 1940 for Give Him R. Corson, K. R. MacKenzie and Emilio Segrè in Berkeley's University (California).

Information obtained of www.wikipedia.org and www.uam.es