0 a chemical element that is radioactive and is the rarest natural element on the Earth's surface -- 砹（地球表面最为稀少的一种放射性化学元素）
The properties of astatine remain a mystery. 砹的属性仍然不为人知。
The lowest element in this group is also a highly radioactive and rare element, astatine.
Fluorine and astatine are halogens.
What is the physical state of astatine at room temperature?
In 2013, on the basis of relativistic modelling, astatine was predicted to be a monatomic metal, with a face-centred cubic crystalline structure.
In contrast, astatine, the second-least stable naturally occurring element, has a half-life of 8.5 hours.
All of its isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours.
The bulk properties of astatine are not known with any great degree of certainty.
A visible piece of astatine would be immediately and completely vaporized due to the heat generated by its intense radioactivity.
