Gold

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Attribution: Alchemist-hp

Animated Gold

History

Known and highly valued from earliest times, gold is found in nature as the free metal and in tellurides; it is very widely distributed and is almost always associated with quartz or pyrite.

Sources

It occurs in veins and alluvial deposits, and is often separated from rocks and other minerals by mining and panning operations. About two thirds of the world's gold output comes from South Africa, and about two thirds of the total U.S. production comes from South Dakota and Nevada. The metal is recovered from its ores by cyaniding, amalgamating, and smelting processes. Refining is also frequently done by electrolysis. Gold occurs in sea water to the extent of 0.1 to 2 mg/ton, depending on the location where the sample is taken. As yet, no method has been found for recovering gold from sea water profitably.

Uses

It is used in coinage and is a standard for monetary systems in many countries. It is also extensively used for jewelry, decoration, dental work, and for plating. It is used for coating certain space satellites, as it is a good reflector of infrared and is inert.

Isotopes

The most common gold compounds are auric chloride and chlorauric acid, the latter being used in photography for toning the silver image. Gold has 18 isotopes; 198Au, with a half-life of 2.7 days, is used for treating cancer and other diseases. Disodium aurothiomalate is administered intramuscularly as a treatment for arthritis. A mixture of one part nitric acid with three of hydrochloric acid is called aqua regia (because it dissolved gold, the King of Metals). Gold is available commercially with a purity of 99.999+%. For many years the temperature assigned to the freezing point of gold has been 1063.0C; this has served as a calibration point for the International Temperature Scales (ITS-27 and ITS-48) and the International Practical Temperature Scale (IPTS-48). In 1968, a new International Practical Temperature Scale (IPTS-68) was adopted, which demands that the freezing point of gold be changed to 1064.43C. The specific gravity of gold has been found to vary considerably depending on temperature, how the metal is precipitated, and cold-worked.

General Info

AtomicNumber
79
Symbol
Au
Name
Gold

Atomic Info

Appearance
AtomicWeight
196.966569(4)
Color
FFD123
ElectronicConfiguration
[Xe] 4f14 5d10 6s1
ElectronegativityInPauling
2.54
AtomicRadiusInPM
144
IonRadiusInPM
137 (+1)
VanDerWaalsRadiusInPM
166
IEinKJmol
890
EAinKJmol
-223
OxidationStates
-1, 1, 2, 3, 5
StandardState
solid
BondingType
metallic
MeltingPoint
1337
BoilingPoint
3129
Density
19.3
State
Transition metal
DiscoveredYear
Ancient