astatín

Astatín is a chemical element with the symbol At and atomic number 85. It is a member of the halogen group, which also includes fluorine, chlorine, bromine, and iodine. Astatín is considered the rarest naturally occurring halogen, with only minute quantities present in Earth's crust and naturally produced through the decay series of uranium and thorium.

As a radioactive element, astatín has no significant stable isotopes; its most stable isotope is astatín-210, which has a half-life of approximately 8.1 hours. Due to its radioactivity and scarcity, astatín has limited practical use and is primarily of interest for scientific research, particularly in nuclear physics and medical applications.

In medical science, astatín's isotopes have been explored for targeted alpha-particle cancer therapy, leveraging their radioactive properties to destroy cancerous cells. Its chemical properties are somewhat similar to iodine, and it can form various compounds such as astatides and astatates, although these compounds are often unstable.

The production of astatín involves complex nuclear reactions, typically generated in cyclotrons by bombarding bismuth targets with alpha particles. Its short half-life and rarity make isolation and handling challenging, which limits extensive study.

Overall, astatín remains an elusive element with primarily scientific significance due to its radioactivity and scarcity, contributing to our understanding of halogen chemistry and radioactive decay processes.