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69Tm168.934
Thulium
LanthanideThulium 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.
Phase: SolidAppearance: silvery gray
2, 8, 18, 31, 8, 2
Physical Properties
Atomic Mass168.934222 u
Density9.32 g/cm³
Melting Point1818 K
Boiling Point2223 K
Molar Heat27.03 J/(mol·K)
Period6
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f13
Semantic Config[Xe] 4f13 6s2
Shells2, 8, 18, 31, 8, 2
Electron Affinity99 kJ/mol
Electronegativity1.25
Ionization Energies
IE1: 596.7 kJ/molIE2: 1160 kJ/molIE3: 2285 kJ/molIE4: 4120 kJ/mol
Discovery
Discovered byPer Teodor Cleve