Chemical Element The Symbol Dy Atomic Number 66 Rare Earth Element Metallic Silver Luster Element Category Lanthanide Standard Atomic Weight 162.500 Magnetic Ordering Paramagnetic at 300 K CAS Registry Number 7429-91-6 
Name, symbol , number dysprosium, Dy, 66 Appearance silvery white Element category lanthanide Group , period , block n/a , 6 , f Standard atomic weight 162.500 Electron configuration [ Xe ] 4f 10 6s 2 2, 8, 18, 28, 8, 2 History Discovery Lecoq de Boisbaudran (1886) Physical properties Phase solid Density (near r.t. ) 8.540 g@cm ?3 Liquid density at m.p. 8.37 g@cm ?3 Melting point 1680 K ,?1407 °C,?2565 °F Boiling point 2840 K,?2562 °C,?4653 °F Heat of fusion 11.06 kJ@mol ?1 Heat of vaporization 280 kJ@mol ?1 Molar heat capacity 27.7 J@mol ?1 @K ?1 Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1378 1523 (1704) (1954) (2304) (2831) Atomic properties Oxidation states 3 , 2, 1 (weakly basic oxide) Electronegativity 1.22 (Pauling scale) Ionization energies 1st: 573.0 kJ@mol ?1 2nd: 1130 kJ@mol ?1 3rd: 2200 kJ@mol ?1 Atomic radius 178 pm Covalent radius 192? pm Miscellanea Crystal structure hexagonal close-packed Magnetic ordering paramagnetic at 300 K Electrical resistivity ( r.t. ) (α, poly) 926 nΩ@m Thermal conductivity 10.7 W@m ?1 @K ?1 Thermal expansion ( r.t. ) (α, poly) 9.9 μm/(m@K) Speed of sound (thin rod) (20 °C) 2710 m@s ?1 Young's modulus (α form) 61.4 GPa Shear modulus (α form) 24.7 GPa Bulk modulus (α form) 40.5 GPa Poisson ratio (α form) 0.247 Vickers hardness 540 MPa Brinell hardness 500 MPa CAS registry number 7429-91-6 Most stable isotopes Main article: Isotopes of dysprosium iso NA half-life DM DE ( MeV ) DP 154 Dy syn 3.0?0 6 y α 2.947 150 Gd 156 Dy 0.06% >1?0 18 y α 2.0108 152 Gd β + β + 1.7579 156 Gd 158 Dy 0.10% 158 Dy is stable with 92 neutrons 160 Dy 2.34% 160 Dy is stable with 94 neutrons 161 Dy 18.91% 161 Dy is stable with 95 neutrons 162 Dy 25.51% 162 Dy is stable with 96 neutrons 163 Dy 24.90% 163 Dy is stable with 97 neutrons 164 Dy 28.18% 164 Dy is stable with 98 neutrons