69
Tm
168.93
Thulium
Element 69 · 168.93 u · f-block
lanthanide
The least abundant naturally occurring lanthanide. Used in portable X-ray devices and high-temperature superconductors.
Phase (STP)
Solid
Melting Point
1545 °C
Boiling Point
1950 °C
Density
9.321 g/cm³
Electronegativity
1.25
Atomic Radius
175 pm
Ionization Energy
597 kJ/mol
Electron Affinity
99 kJ/mol
Discovered
1879 · Per Teodor Cleve
Electron Configuration
[Xe] 4f13 6s2
Electron Orbitals
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