Gold - ₇₉Au: physical properties

Gold is a soft metal with a number of interesting physical properties. Gold is both malleable and ductile. Gold is a heavy metal (density 19.3 g cm^-3) and one gram of gold can be hammered out into a thin sheet of gold a metre in area, and just 230 atoms or so thick. Gold leaf is translucent and the transmitted light is greenish blue (gold metal reflects yellow and red, leaving the greenish blue colour. One gram of gold can be drawn into a thin wire 165 metres long and just 20 micrometres thick. X-ray data suggest electrons from filled d bands near the electron energy surface of the s-p conduction band are excited by near ultraviolet and blue energies, giving rise to the characteristic gold colour of the metal.

Density properties

• Density of solid: 19300 kg m^‑3
• Molar volume: 10.21 cm³

Elastic properties

• Young's modulus: 78 GPa
• Rigidity modulus: 27 GPa
• Bulk modulus: 220 GPa
• Poisson's ratio: 0.44 (no units)

Hardnesses

• Mineral hardness: 2.5 (no units)
• Brinell hardness: 2450 MN m^-2
• Vickers hardness: 216 MN m^-2

Electrical properties

• Electrical resistivity: 2.2 × 10^‑8 Ω m; or mΩ cm

Heat and conduction

• Thermal conductivity: 320 W m^‑1 K^‑1
• Coefficient of linear thermal expansion: 14.2 × 10^‑6 K^‑1

Optical properties

The image above is a virtual representation of gold metal calculated by Patrick Callet using the complex diectric function of the element only.

• Reflectivity: 95 %
• Refractive index: (no data) (no units)

Acoustic properties

• Velocity of sound: 1740 m s^‑1