Periodic Table
69
Tm
168.93
Thulium
LanthanoidRarest stable lanthanoid; portable X-ray sources.
Electronic Configuration
[Xe] 4f¹³ 6s²or1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 4f¹³ 6s²
Electron shells
2e⁻n=1
8e⁻n=2
18e⁻n=3
31e⁻n=4
8e⁻n=5
2e⁻n=6
Properties
Atomic number
69
Atomic mass
168.93 u
Category
Lanthanoid
Block / Group / Period
f · — · 6
Valence electrons
2
Oxidation states
+3
Electronegativity
1.25
Atomic radius
222 pm
Ionization energy
597 kJ/mol
Electron affinity
50 kJ/mol
Melting point
1818 K / 1545 °C
Boiling point
2223 K / 1950 °C
Density
9.321 g/cm³
State at 25 °C
solid
Personal Notes
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