Thulium, 69 General properties Pronunciation Template:Infobox element/pronunciation Appearance silvery gray Standard atomic weight (A r, standard ) Template:Infobox element/standard atomic weight Mass number Template:Infobox element/symbol-to-most-stable-isotope (most stable isotope)Thulium in the periodic table Template:Infobox element/periodic table Atomic number (Z ) 69 Group Template:Infobox element/group Period period 6 Block f-block Element category Template:Infobox element/category format Electron configuration [Xe ] 4f13 6s2 Electrons per shell
2, 8, 18, 31, 8, 2 Physical properties Phase at STP solid Melting point 1818 K (1545 °C, 2813 °F) Boiling point 2223 K (1950 °C, 3542 °F) Density (near r.t. ) 9.32 g/cm3 when liquid (at m.p. ) 8.56 g/cm3 Heat of fusion 16.84 kJ/mol [[Enthalpy of vaporization|Heat of Template:Engvar ]] 191 kJ/mol Molar heat capacity 27.03 J/(mol·K) [[Vapor pressure|Template:Engvar pressure Atomic properties Oxidation states Template:Infobox element/symbol-to-oxidation-state Electronegativity Pauling scale: 1.25 [[Ionization energy|Template:Engvar energies]] 1st: 596.7 kJ/mol 2nd: 1160 kJ/mol 3rd: 2285 kJ/mol Atomic radius empirical: 176 pm Covalent radius 190±10 pm Template:Infobox element/spectral lines Other properties Crystal structure Template:Infobox element/crystal structure Thermal expansion poly: 13.3 µm/(m·K) (at r.t. ) Thermal conductivity 16.9 W/(m·K) Electrical resistivity poly: 676 nΩ·m (at r.t. ) Magnetic ordering paramagnetic (at 300 K)Magnetic susceptibility +25,500·10−6 cm3 /mol (291 K)[1] Young's modulus 74.0 GPa Shear modulus 30.5 GPa Bulk modulus 44.5 GPa Poisson ratio 0.213 Vickers hardness 470–650 MPa Brinell hardness 470–900 MPa CAS Number 7440-30-4 History Naming after Thule , a mythical region in Scandinavia Discovery and first isolationPer Teodor Cleve (1879)Main isotopes of thulium Template:Infobox element/isotopes table | references
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↑ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics . Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4 