Astatine is a synthetic, radioactive metallic halogen element with the atomic number 85. As a member of the halogens group, it exhibits chemical properties related to other halogens, although its high degree of radioactivity makes its handling and study challenging. Due to its instability and limited natural occurrence, it is generally difficult to isolate in bulk quantities. In scientific and industrial contexts, its decay properties have led to investigation into its potential use in radiopharmaceuticals, where it can be incorporated into compounds for therapeutic applications within medicine.