Palladium is the lightest of the platinum group and very malleable and ductile when pure. It resists oxidation at ordinary temperatures. It absorbs a considerable amount of hydrogen gas. It is appreciably volatile at high temperatures. At red heat it is converted to the oxide.;Stable isotopes: (102)Pd, 1.02%; (1.4)Pd, 11.14%; (105)Pd, 22.23%; (106)Pd, 27.33%; (108)Pd, 26.46%; (110)Pd, 11.72%;Usual valency, 2,4; ionic radius, 65 pm, crystal structure, face-centered cubic; lattice constant, 389 pm; reflectance, 54%; thermal expansion, 11.11X10+6 °C-1; magnetic susceptibility, 5.23X10-6 cu cm/g; work function, 4.99 eV; Young's modulus, 1.24X10+8 kN/sq m; ultimate tensile strength, 180-200 MPa; Poisson's ratio, 0.39; Vicker's hardness, 40; temperature coefficient of resistance 3.8X10-3 K-1; electrical resistivity at 0 °C, 9.93 microohm-cm; thermal conductivity, 75 W/m K;Palladium is stable in air, even at elevated temperatures; shows no corrosion or tarnishing in hydrogen sulfide atmospheres.;Enthalpy of formation at 298.15 K: 378.2 kJ/mol (gas); molar heat capacity at 298.15 K: 26.0 J/mol K (crystal), 20.8 J/mol K (gas);Enthalpy of fusion: 16.74 kJ/mol at 1554.9 °C
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