Gold ( Au )

Material Information

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General Description:  

This metal has been known since prehistoric times

Gold is a soft metal with a characteristic yellow colour. It is the most malleable and ductile of any element. It is unaffected by air, water, alkalis and acids, with the exception of "aqua regia", HNO3/HCl. The fact that it is chemically unreactive means that it is often found in its natural state. It is a good thermal and electrical conductor and has excellent reflective properties to both light and infrared. It has an abundance in the earth's crust of 0.0011 ppm.

Most of the metal is retained for use as bullion reserves, but some is used within the electronics and jewellery industries, where it is frequently alloyed with other elements to improve the mechanical properties of the metal (e.g. copper and silver). Other uses for the metal are as a heat reflecting coating for glass as well as as a decorative medium.

   

Atomic Properties
     
Atomic number 79
Atomic radius - Goldschmidt ( nm ) 0.144
Atomic weight ( amu ) 196.9665
Crystal structure Face centred cubic
Electronic structure Xe 4f14 5d1O 6s1
Ionisation potential No. eV
1 9.22
2 20.5
Natural isotope distribution Mass No. %
197 100
Photo-electric work function ( eV ) 4.8
Thermal neutron absorption cross-section ( Barns ) 98.8
Valences shown 1,3

Electrical Properties
     
Electrical resistivity @20C ( µOhmcm ) 2.20
Temperature coefficient @0-100C ( K-1 ) 0.0040
Thermal emf against Pt (cold 0C - hot 100C) ( mV ) +0.74

Mechanical Properties
     
Material condition Soft Hard Polycrystalline
Bulk modulus ( GPa ) 171
Hardness - Vickers 20-30 60
Poisson's ratio 0.42
Tensile modulus ( GPa ) 78.5
Tensile strength ( MPa ) 130 220
Yield strength ( MPa ) 205

Physical Properties
     
Boiling point ( C ) 3080
Density @20C ( g cm-3 ) 19.30
Melting point ( C ) 1064.4

Thermal Properties
     
Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 14.1
Latent heat of evaporation ( J g-1 ) 1738
Latent heat of fusion ( J g-1 ) 64.9
Specific heat @25C ( J K-1 kg-1 ) 129
Thermal conductivity @0-100C ( W m-1 K-1 ) 318


All information and technical data are given as a guide only. Although every effort has been made to ensure that the information is correct, no warranty is given as to its completeness or accuracy.

Standard products are available in these forms
Foil Insulated Wire Lump Mesh Microfoil Microleaf Powder Rod Single Crystal Sphere Sputtering Target Tube Wire

Choose a form to search our on-line catalogue

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