Facts about Gold

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Chemical and Physical Properties

Chemical Symbol Au (Aurum)
Atomic Number 79
Chemical Series Transition metals
Atomic mass 196.97
Density 19.30 g·cm-3
Melting Point 1064.18 °C
Boiling Point 2856°C
Heat of Vaporisation 324 kJ/mol
Heat of Fusion 12.55 kJ/mol
Specific Heat Capacity        0,129 kJ/kg.K
Hardness 2.5 (Mohs)
Thermal conductivity (300 K) 318 W/(m·K)

 

Notable Characteristics

Gold is a chemical element with the symbol Au which comes from its Latin name Aurum and means glowing dawn. Gold is a precious metal which is one of the most difficult to effect on and one of the most valuable metals that exists in nature.

Gold has many special properties; because of its softness, it is easy to shape and melt. A gramme of gold can be beaten into a hundred metres long thread. Gold conducts electricity and heat well. Gold does not corrode, discolour or rust when exposed to air or water. Concentrated acids and bases cannot effect gold either. That is why golden objects maintain their shine a very long time while other metals like iron, copper and silver get dark deposits from oxide and sulphides over time.

Gold is a heavy metal; its density is 19,32 kg/dm3. Gold melts at the temperature of 1 063ºC and its boiling point is 2 940ºC.

Applications

The biggest branch of the gold industry is jewellery. In the past years, the consumption in this branch has outrun the mining production. Pure gold is designated as 24 carats or a thousandth of fine gold. This metal is soft. Gold is usually hardened by alloying it with other metals like silver and copper. The typical gold grade in jewellery is 18 carats when the alloy contains 75 % gold and 25 % other metals like silver and copper.

Because of its many special properties, gold is also used in industry. Because of conducting well and being corrosion resistant, gold is used for coating contact areas in electronics and telecom industry’s high technological products, such as in semiconductors, circuit boards and microchips. It is even used in window glass and by optics to moderate heat and light transmission. The dental industry is also a considerable user. An increasing amount of gold is also used in the medical industry.


Figure. Identifiable gold demand excluding central banks in the year 2008. Source: GMFS.