Ultra Dry Thulium Fluoride

See more Thulium products. Thulium (atomic symbol: Tm, atomic number: 69) is a Block F, Group 3, Period 6 element with an atomic weight of 168.93421. The number of electrons in each of Thulium's shells is [2, 8, 18, 31, 8, 2] and its electron configuration is [Xe]4f¹³6s². The thulium atom has a radius of 176 pm and a Van der Waals radius of 227 pm. In its elemental form, thulium has a silvery-gray appearance. Thulium is representative of the other lanthanides (rare earths) and similar in chemistry to yttrium. It is the least abundant of the rare earth elements. Thulium emits blue upon excitation, and is used in flat panel screens that depend critically on bright blue emitters. Thulium was discovered and first isolated by Per Teodor Cleve in 1879. It is named after "Thule," which is the ancient name of Scandinavia.

Fluorine is a Block P, Group 17, Period 2 element. Its electron configuration is [He]2s²2p⁵. The fluorine atom has a covalent radius of 64 pm and its Van der Waals radius is 135 pm. In its elemental form, CAS 7782-41-4, fluorine gas has a pale yellow appearance. Fluorine was discovered by André-Marie Ampère in 1810. It was first isolated by Henri Moissan in 1886.