69Tm168.934
Lanthanidef-block
Thulium
Element 69 on the periodic table, symbol Tm, group 3, period 6.
Thulium is a chemical element with symbol Tm and atomic number 69. It is the thirteenth and antepenultimate (third-last) element in the lanthanide series. Like the other lanthanides, the most common oxidation state is +3, seen in its oxide, halides and other compounds.
Appearance: silvery gray
Properties
- Atomic Number
- 69
- Atomic Mass
- 168.9342 u
- Group
- 3
- Period
- 6
- Block
- f-block
- Category
- Lanthanide
- State at 25 °C
- Solid
- Melting Point
- 1,818 K · 1,544.9 °C
- Boiling Point
- 2,223 K · 1,949.9 °C
- Density
- 9.32 g/cm³
- Atomic Radius
- 175 pm
- Electronegativity
- 1.25
- Oxidation States
- +3
- Abundance in Crust
- 0.52 mg/kg
- Discovered
- 1879
- Discovered By
- Per Teodor Cleve
Electron Configuration
[Xe] 4f13 6s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f13
Ionisation Energies (kJ/mol)
- 1. 596.7
- 2. 1,160
- 3. 2,285
- 4. 4,120
Elements near Thulium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.