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Chemical element with atomic number 79 (Au)
Gold, 79 Au Appearance Metallic yellow
Atomic number (Z ) 79 Group group 11 Period period 6 Block d-block Electron configuration [Xe ] 4f14 5d10 6s1 Electrons per shell 2, 8, 18, 32, 18, 1 Phase at STP solid Melting point 1337.33 K (1064.18 °C, 1947.52 °F) Boiling point 3243 K (2970 °C, 5378 °F) Density (at 20° C) 19.283 g/cm3 [ 3] when liquid (at m.p. ) 17.31 g/cm3 Heat of fusion 12.55 kJ/mol Heat of vaporization 342 kJ/mol Molar heat capacity 25.418 J/(mol·K) Vapor pressure
P (Pa)
1
10
100
1 k
10 k
100 k
at T (K)
1646
1814
2021
2281
2620
3078
Oxidation states common: +3
−3,? −2,? −1,[ 4] 0, +1,[ 5] +2,[ 4] +5[ 4] Electronegativity Pauling scale: 2.54 Ionization energies 1st: 890.1 kJ/mol 2nd: 1980 kJ/mol Atomic radius empirical: 144 pm Covalent radius 136±6 pm Van der Waals radius 166 pm Spectral lines of goldNatural occurrence primordial Crystal structure face-centered cubic (fcc) (cF4 ) Lattice constant a = 407.86 pm (at 20 °C)[ 3] Thermal expansion 14.13× 10−6 /K (at 20 °C)[ 3] Thermal conductivity 318 W/(m⋅K) Electrical resistivity 22.14 nΩ⋅m (at 20 °C) Magnetic ordering diamagnetic [ 6] Molar magnetic susceptibility −28.0× 10−6 cm3 /mol (at 296 K)[ 7] Tensile strength 120 MPa Young's modulus 79 GPa Shear modulus 27 GPa Bulk modulus 180 GPa[ 8] Speed of sound thin rod 2030 m/s (at r.t. ) Poisson ratio 0.4 Mohs hardness 2.5 Vickers hardness 188–216 MPa Brinell hardness 188–245 MPa CAS Number 7440-57-5 Naming from Latin aurum 'gold' Discovery In the Middle East (before 6000 BCE ) Symbol "Au": from Latin aurum
Category: Gold | references
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