| Name | thulium |
|---|---|
| Symbol | Tm |
| Atomic Weight | 168.93421 |
| Atomic Number | 69 |
| CAS ID | 7440-30-4 |
| Group Number | |
| Group Name | Lanthanoid |
| Period Number | 6 |
| Origin of Name | Named after Thule, ancient Scandinavia. |
| Year Discovered | 1879 |
| Discovery Credits | Discovered by P. T. Cleve at Uppsala, Sweden. |
| Class | Metallic |
| Color | Silvery White |
| Standard State | Solid at 77 F & 298 K |
| Description | Silvery metal, rarest of the lanthanide group. Tarnishes in air and
reacts with water. Few uses but some employed as a radiation source in portable x-ray equipment. Diagnostic tests: |