| Name | astatine |
|---|---|
| Symbol | At |
| Atomic Weight | 209.99 |
| Atomic Number | 85 |
| CAS ID | 7440-68-8 |
| Group Number | 17 |
| Group Name | Halogen |
| Period Number | 6 |
| Origin of Name | Greek, astatos = "unstable." |
| Year Discovered | 1940 |
| Discovery Credits | Produced by D. R. Corson, K. R. Mackenzie, and E. Segre at the University of California, USA. |
| Class | Semi-metallic |
| Color | Metallic Grey |
| Standard State | Solid at 77 F & 298 K |
| Description | Radioactive non-metallic element which does not occur naturally. Relatively unknown because of the short half-life. |