Astatine is located in the sixth period and seventeenth group in the periodic table of elements. It is extremely radioactive with a half-life of only a few hours. It's appearance is unknown with a theoretical melting point of 302 degrees Celsius. It was first identified in 1940 Emilio Segre.  

Astatine is sometimes used in radiotherapy due to its extreme radioactivity. It doesn't have many other uses outside of research.