Promethium, 61 General properties Pronunciation Template:Infobox element/pronunciation Appearance metallic 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)Promethium in the periodic table Template:Infobox element/periodic table Atomic number (Z ) 61 Group Template:Infobox element/group Period period 6 Block f-block Element category Template:Infobox element/category format Electron configuration [Xe ] 4f5 6s2 Electrons per shell
2, 8, 18, 23, 8, 2 Physical properties Phase at STP solid Melting point 1315 K (1042 °C, 1908 °F) Boiling point 3273 K (3000 °C, 5432 °F) Density (near r.t. ) 7.26 g/cm3 Heat of fusion 7.13 kJ/mol [[Enthalpy of vaporization|Heat of Template:Engvar ]] 289 kJ/mol Atomic properties Oxidation states Template:Infobox element/symbol-to-oxidation-state Electronegativity Pauling scale: 1.13 (?) [[Ionization energy|Template:Engvar energies]] 1st: 540 kJ/mol 2nd: 1050 kJ/mol 3rd: 2150 kJ/mol Atomic radius empirical: 183 pm Covalent radius 199 pm Template:Infobox element/spectral lines Other properties Crystal structure Template:Infobox element/crystal structure Thermal expansion 9.0 µm/(m·K)[1] r.t. ) Thermal conductivity 17.9 W/(m·K) Electrical resistivity est. 0.75 µΩ·m (at r.t. ) Magnetic ordering paramagnetic [2] Young's modulus α form: est. 46 GPa Shear modulus α form: est. 18 GPa Bulk modulus α form: est. 33 GPa Poisson ratio α form: est. 0.28 CAS Number 7440-12-2 History Discovery Chien Shiung Wu , Emilio Segrè , Hans Bethe (1942) First isolation Charles D. Coryell , Jacob A. Marinsky , Lawrence E. Glendenin , Harold G. Richter (1945) Named by Grace Mary Coryell (1945) Main isotopes of promethium Template:Infobox element/isotopes table | references
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