Chapter 1: Geography Is Destiny
#69 Mass-169 period-6 it's Electron Config.- 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^6 4d^10 4f^13 5s^2 5p^6 6s^2. Thulium is in the lanthanide category. Thulium can be used to create lasers. Thulium was discovered by Per Teodor Cleave in 1879. He named this element after Thule, and Ancient Greek name associated with Iceland. Thulium is the least abundant of the rare earth metals.