noun
- A radioactive chemical element with atomic number 85, belonging to the halogen group; the rarest naturally occurring element on Earth.
Usage: chemistry; symbol: At; highly unstable with no stable isotopes
Examples
- Astatine is the rarest naturally occurring element in the Earth's crust.
- Scientists study astatine because of its potential applications in nuclear medicine.
- The element astatine was first synthesized in 1940.
- Astatine belongs to the halogen family on the periodic table.
- Due to its extreme radioactivity, astatine is difficult to isolate and study.