94 neptunium ← plutonium → americium Sm ↑ Pu ↓ (Uqq) periodic table General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [ Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r.t.) 19.816 g/cm³ Liquid density at m.p. 16.63 g/cm³ Melting point 912.5 K (639.4 ° C, 1182.9 ° F) Boiling point 3501 K (3228 ° C, 5842 ° F) Heat of fusion 2.82 kJ/mol Heat of vaporization 333.5 kJ/mol Heat capacity (25 °C) 35.5 J/(mol·K) Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 1756 1953 2198 2511 2926 3499 Atomic properties Crystal structure monoclinic Oxidation states 6, 5, 4, 3 ( amphoteric oxide) Electronegativity 1.28 ( Pauling scale) Ionization energies 1st: 584.7 kJ/mol Atomic radius 175 pm Miscellaneous Magnetic ordering no data Electrical resistivity (0 °C) 1.460 µΩ·m Thermal conductivity (300 K) 6.74 W/(m·K) Thermal expansion (25 °C) 46.7 µm/(m·K) Speed of sound (thin rod) (20 °C) 2260 m/s Young's modulus 96 GPa Shear modulus 43 GPa Poisson ratio 0.21 CAS registry number 7440-07-5 Notable isotopes Main article: Isotopes of plutonium iso NA half-life DM DE ( MeV) DP 238Pu syn 88 y SF - - α 5.5 234 U 239Pu trace 24.1×103 y SF - - α 5.245 235 U 240Pu syn 6.5×103 y SF - - β 0.005 240 Am 241Pu syn 14 y α 4.9 MeV U SF - - 242Pu syn 3.73×105 y SF - - α 4.984 238 U 244Pu syn 8.08×107 y α 4.666 240 U SF - - References
