Gold, Au

Gold is a chemical element with the symbol Au (from the Latin aurum, meaning shining dawn) and atomic number 79. It is a highly sought-after precious metal which, for many centuries, has been used as money, a store of value and in jewelry. The metal occurs as nuggets or grains in rocks, underground "veins" and in alluvial deposits. It is one of the coinage metals. Gold is dense, soft, shiny and the most malleable and ductile of the known metals. Pure gold has a bright yellow color traditionally considered attractive.

Gold formed the basis for the gold standard used before the fiat currency monetary system was employed by the International Monetary Fund (IMF) and the Bank for International Settlements (BIS). It is specifically against IMF regulations to base any currency against gold for all IMF member states. The ISO currency code of gold bullion is XAU.

Modern industrial uses include dentistry and electronics, where gold has traditionally found use because of its good resistance to oxidative corrosion.

Chemically, gold is a trivalent and univalent transition metal. Gold does not react with most chemicals, but is attacked by chlorine, fluorine, aqua regia and cyanide. Gold dissolves in mercury, forming amalgam alloys, but does not react with it. Gold is insoluble in nitric acid, which will dissolve silver and base metals, and this is the basis of the gold refining technique known as "inquartation and parting". Nitric acid has long been used to confirm the presence of gold in items, and this is the origin of the colloquial term "acid test," referring to a gold standard test for genuine value.

Technical Data
Symbol Au Density (20°C)/gcm-3 19.32
Atomic number 79 Melting point /°C 1064
No. of naturally occurring isotopes 1 Boiling point /°C 2808
Atomic weight 196.9665 ΔHvap/kJmol-1 12.8
Electronic configuration [Xe]4f145d106s4 ΔHfus/kJmol-1 343(+/-U
Metal radius (12coordinate)/pm 144 ΔHf(monoatomic gas)/kJmol-1 379(+/-8)
Effective ionic radius)6-coord)/pm V 57 Ionization energy/kJmol-1 I 889.9
Effective ionic radius(6-coord)/pm III 85 Ionization energy/kJmol-1 II 1973.3
Effective ionic radius(6-coord)/pm II - Ionization energy/kJmol-1 III -2895
Effective ionic radius(6-coord)/pm I 137 Electrical resistivity  
Electronegativity χ 2.4 (20°C)/μohm cm 2.35
Evaporation Techniques
Temperature (oC) @Vap. Pressure Techniques Remarks
10-8 Torr 10-6 Torr 10-4 Torr Electron Beam Crucible Coil Boat
807 947 1132 Excellent Al2O3, BN & Vitreous Graphite Tungsten Tungsten, Molybdenum coated Al2O3 Films soft. Not very adherent.

Evaporation Materials
G4-5002-N pellets 6mm diameter x 6mm long
G4-5005-M granules 1-3 mm
G4-5011-M fine grain
G4-5013-M pellets 3mm diameter x 3mm long

The foils are available in either rectangular or circular shape. Please enter width and length or diameter of the required foil.

Foil
G4-3009-F 0.015mm
G4-3000-F 0.001" (0.025mm)
G4-3001-F 0.002" (0.051mm)
G4-3002-F 0.003" (0.076mm)
G4-3003-F 0.004" (0.102mm)
G4-3004-F 0.005" (0.127mm)
G4-3005-F 0.006" (0.152mm)
G4-3006-F 0.007" (0.178mm)
G4-3007-F 0.008" (0.203mm)
Powder
G4-10000-P -100 mesh
G4-10002-P -325 mesh
Rods
G4-2000-R 0.0625" (1.58mm)
G4-2001-R 0.125" (3.175mm)
G4-2002-R 0.250" (6.35mm)
G4-2003-R 0.500" (12.7mm)
G4-2004-R 0.625" (15.88mm)
G4-2005-R 0.750" (19.05mm)
G4-2006-R 1" (25.4mm)
Sheet
G4-4001-S 0.015" (0.381mm)
G4-4002-S 0.020" (0.508mm)
G4-4003-S 0.030" (0.762mm)
G4-4004-S 0.040" (1.0mm)
G4-4005-S 0.050" (1.27mm)
G4-4006-S 0.060" (1.524mm)
G4-4007-S 0.0625" (1.588mm)
G4-4008-S 0.125" (3.175mm)
G4-4009-S 0.250" (6.35mm)
G4-4010-S 0.375" (9.525mm)
G4-4011-S 0.500" (12.7mm)
G4-4012-S 0.750" (19.05mm)
G4-4013-S 1" (25.4mm)
Wire
G4-1000-W 0.001" (0.025mm)
G4-1001-W 0.002" (0.050mm)
G4-1003-W 0.004" (0.1mm)
G4-1007-W 0.008" (0.2mm)
G4-1011-W 0.020" (0.5mm)
G4-1013-W 0.040" (1.0mm)
G4-1017-W 0.080" (2.0mm)