| Gold, Au | |
|---|---|
| Categories: | MetalNonferrous MetalPrecious MetalGold AlloyPure Element |
| Material Notes: | Gold is a noble metal and does not react with oxygen under ambient conditions. Therefore gold does not tarnish, leading to its use in jewelry and coinage. The same resistance to oxidation and other harsh chemical environments leads to its use in industrial applications such as labware and electrical contacts. Although it does not typically form oxides, it will form compounds with other metals and is rarely found in its pure form. It is usually associated with silver and often with mercury. When the silver content is a high, the metal is called electrum, a naturally occurring gold-silver alloy. Gold is also found in tellurides and ore containing quartz where it is either openly visible or enclosed in particles of sulfide minerals such as chalcopyrite, pyrrhotite, pyrite, and arsenopyrite. Gold in its pure form is a very soft metal, so it is often alloyed with other metals for increased strength and hardness. When gold is alloyed, its ductility is diminished, but its malleability remains constant, except when large amounts of copper are added. Red or pink gold (also called rose gold) is gold that contains large percentages of copper and a small amount of silver. Green gold is usually gold alloyed with additional silver or with silver that has a small percentage of copper. White gold is usually 75% gold and 25% nickel (or nickel, zinc, and sometimes copper). Formerly white gold was made with silver and/or palladium, but white gold made with nickel and zinc is harder, cheaper, and has better melting characteristics. |
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Export data to your CAD/FEA program| Physical Properties | Metric | English | Comments | ||
|---|---|---|---|---|---|
| Density | 19.32 g/cc | 0.6980 lb/in³ | |||
Vapor Pressure  | 0.001013 bar @Temperature 1770 °C | 0.7598 torr @Temperature 3220 °F | |||
| 0.01013 bar @Temperature 2036 °C | 7.598 torr @Temperature 3697 °F | ||||
| 0.1013 bar @Temperature 2383 °C | 75.98 torr @Temperature 4321 °F | ||||
| 1.013 bar @Temperature 2857 °C | 759.8 torr @Temperature 5175 °F | ||||
| Chemical Properties | Metric | English | Comments | ||
| Atomic Mass | 196.9666 | 196.9666 | 196.96655 – 1995 | ||
| Atomic Number | 79 | 79 | |||
| Thermal Neutron Cross Section | 99 barns/atom | 99 barns/atom | |||
| X-ray Absorption Edge | 0.15344 Å | 0.15344 Å | K | ||
| 0.86378 Å | 0.86378 Å | LI | |||
| 0.90277 Å | 0.90277 Å | LII | |||
| 1.04028 Å | 1.04028 Å | LIII | |||
| Electrode Potential | 1.68 V | 1.68 V | |||
| Electronegativity | 2.4 | 2.4 | Pauling | ||
| Ionic Radius | 0.850 Å | 0.850 Å | Crystal Ionic Radius for Valence +3 | ||
| 1.37 Å | 1.37 Å | Crystal Ionic Radius for Valence +1 | |||
| Electrochemical Equivalent | 2.45 g/A/h | 2.45 g/A/h | |||
| Mechanical Properties | Metric | English | Comments | ||
| Hardness, Vickers | 25 | 25 | |||
| Tensile Strength, Ultimate | 120 MPa | 17400 psi | Annealed | ||
| Elongation at Break | 30 % | 30 % | |||
| Modulus of Elasticity | 77.2 GPa | 11200 ksi | 60% Cold Worked | ||
| Poissons Ratio | 0.42 | 0.42 | |||
| Shear Modulus | 27.2 GPa | 3950 ksi | 60% Cold Worked; Calculated Value | ||
| Electrical Properties | Metric | English | Comments | ||
| Electrical Resistivity | 0.00000220 ohm-cm | 0.00000220 ohm-cm | |||
| Magnetic Susceptibility | -1.42e-7 | -1.42e-7 | cgs/g | ||
| Thermal Properties | Metric | English | Comments | ||
| Heat of Fusion | 66.2 J/g | 28.5 BTU/lb | |||
| Heat of Vaporization | 1738 J/g | 747.7 BTU/lb | |||
| CTE, linear | 14.4 µm/m-°C @Temperature 20.0 – 100 °C | 8.00 µin/in-°F @Temperature 68.0 – 212 °F | |||
| 14.6 µm/m-°C @Temperature 250 °C | 8.11 µin/in-°F @Temperature 482 °F | ||||
| 15.2 µm/m-°C @Temperature 500 °C | 8.44 µin/in-°F @Temperature 932 °F | ||||
| 16.7 µm/m-°C @Temperature 950 °C | 9.28 µin/in-°F @Temperature 1740 °F | ||||
| Specific Heat Capacity | 0.128 J/g-°C @Temperature 25.0 °C | 0.0306 BTU/lb-°F @Temperature 77.0 °F | |||
| 0.133 J/g-°C @Temperature 227 °C | 0.0318 BTU/lb-°F @Temperature 441 °F | ||||
| 0.142 J/g-°C @Temperature 627 °C | 0.0339 BTU/lb-°F @Temperature 1160 °F | ||||
| 0.159 J/g-°C @Temperature 1227 °C | 0.0380 BTU/lb-°F @Temperature 2241 °F | ||||
| 0.163 J/g-°C @Temperature 1027 °C | 0.0390 BTU/lb-°F @Temperature 1881 °F | ||||
| 0.166 J/g-°C @Temperature 1127 °C | 0.0397 BTU/lb-°F @Temperature 2061 °F | ||||
| 0.170 J/g-°C @Temperature 1063 °C | 0.0406 BTU/lb-°F @Temperature 1945 °F | ||||
| Thermal Conductivity | 301 W/m-K | 2090 BTU-in/hr-ft²-°F | |||
| Melting Point | 1064.43 °C | 1947.97 °F | |||
| Boiling Point | 2856 °C | 5173 °F | |||
| Optical Properties | Metric | English | Comments | ||
| Emissivity (0-1) | 0.040 @Temperature 100 °C | 0.040 @Temperature 212 °F | total spectrum | ||
| Reflection Coefficient, Visible (0-1) | 0.27 | 0.27 | 400 nm | ||
| 0.50 | 0.50 | 500 nm | |||
| 0.85 | 0.85 | 600 nm | |||
| Component Elements Properties | Metric | English | Comments | ||
| Gold, Au | 100 % | 100 % | |||
| Descriptive Properties | |||||
| CAS Number | 7440-57-5 | ||||
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