Astatine

**Definition:** 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.

**Tree numbers:** - D01.268.271.110 - D01.268.380.075 - D01.496.749.305.110