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Thulium (Tm)
Element with atomic number 69, category: Lanthanide, a solid at room temperature.
Element 69 of 118
Lanthanide
Thulium
Group 15, Period 6 (lanthanide series)
Common Uses
Lasers
Electron Diagram
About Thulium
Thulium is a chemical element with the symbol Tm and atomic number 69, meaning every atom has 69 protons in its nucleus. It is classed as Lanthanide and is a solid at room temperature. Its atomic mass is about 168.934 atomic mass units (u).
On the periodic table, Thulium sits in group 15, period 6 (lanthanide series), which determines how many electron shells it has and how it tends to react with other elements.
Uses of Thulium
In daily life and industry, Thulium is used for Lasers. These uses are closely tied to the typical properties of elements in the Lanthanide category.
Electron Structure of Thulium
Using a simplified electron shell model (at most 2 electrons in the first shell, 8 in the second, 18 in the third, and so on), Thulium has 5 electron shells, with an approximate arrangement of 2, 8, 18, 32, 9 electrons from the innermost shell to the outermost. This is a simplified learning model, not the full electron configuration that accounts for the s, p, d and f subshells.
Explore Other Elements
Want to see another element or try the element symbol quiz? Go back to the Interactive Periodic Table to explore all 118 chemical elements.