General | |||||||||||||
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Name, Symbol, Number | Gold, Au, 79 | ||||||||||||
Chemical series | transition metals | ||||||||||||
Group, Period, Block | 11 (IB), 6 , d | ||||||||||||
Density, Hardness | 19300 kg/m3, 2.5 | ||||||||||||
Appearance | Metallic yellow | ||||||||||||
Atomic Properties | |||||||||||||
Atomic weight | 196.96655 amu | ||||||||||||
Atomic radius (calc.) | 135 (174) pm | ||||||||||||
Covalent radius | 144 pm | ||||||||||||
van der Waals radius | 166 pm | ||||||||||||
Electron configuration | [Xe]4f14 5d10 6s1 | ||||||||||||
e- 's per energy level | 2, 8, 18, 32, 18, 1 | ||||||||||||
Oxidation states (Oxide) | 3, 1 (amphoteric) | ||||||||||||
Crystal structure | Cubic face centered | ||||||||||||
Physical Properties | |||||||||||||
State of matter | solid (__) | ||||||||||||
Melting point | 1337.33 K (1947.52 °F) | ||||||||||||
Boiling point | 3129 K (5173 °F) | ||||||||||||
Molar volume | 10.21 ×10-3 m3/mol | ||||||||||||
Heat of vaporization | 334.4 kJ/mol | ||||||||||||
Heat of fusion | 12.55 kJ/mol | ||||||||||||
Vapor pressure | 0.000237 Pa at 1337 K | ||||||||||||
Speed of sound | 1740 m/s at 293.15 K | ||||||||||||
Miscellaneous | |||||||||||||
Electronegativity | 2.54 (Pauling scale) | ||||||||||||
Specific heat capacity | 128 J/(kg*K) | ||||||||||||
Electrical conductivity | 45.2 106/m ohm | ||||||||||||
Thermal conductivity | 317 W/(m*K) | ||||||||||||
1st ionization potential | 890.1 kJ/mol | ||||||||||||
2nd ionization potential | 1980 kJ/mol | ||||||||||||
Most Stable Isotopes | |||||||||||||
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SI units & STP are used except where noted. |
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Gold is also a good conductor of heat and electricity and is not affected by air and most reagents. It is quite chemically unalterable by heat, moisture, and most corrosive agents and therefore is well suited for its use in coin and jewelry.
The color of solid gold as well as of the intensely colored, often purple, colloidal solutions that can be made from it is caused by the fact that the plasmon frequency of this element lies in the visible range, which causes red and yellow light to be reflected and blue light to be absorbed. Native gold contains usually eight to ten per cent silver, but often much more. As the amount of silver increases, the color becomes whiter and the specific gravity lower.
Alloys with with copper yield a redder metal, alloys with iron are green, aluminum alloys are purple. Jewelry made with combinations of colored gold is sold in the western United States to the tourist trade as Black Hills gold.
Common oxidation states of gold include +1 and +3.
Since it is a good reflector of both infrared and is inert light, it is used for the protective coatings on many artificial satellites.
Gold has long been considered one of the most precious metals, and its value has been used as the standard for many currencies (known as the gold standard) in history.
The primary goal of the alchemists was to produce gold from other substances, such as lead - Though they were never successful at this attempt, the alchemists promoted an interest in what can be done with substances, and this laid a foundation for today's chemistry. Many competitions award a gold medal[?] to the winner, silver to the second-place finisher, and bronze to the third. The largest gold depository in the world is the U.S. Federal Reserve Bank.
Historical gold was used to back currency in a system known as the gold standard in which one unit of currency was equivalent to a certain amount of gold.
For a very long time the value of gold was set by the United States at $20.67 per troy ounce but in 1934 the value of gold was fixed at $35.00 per troy ounce. Because of a gold crisis, on March 17, 1968, a two-tiered pricing scheme was established whereby gold was still used to settle international accounts at the old $35.00 per troy ounce but the price of gold on the private market was allowed to fluctuate, this two-tiered pricing system was abandoned in 1975 when the price of gold was allowed to fluctuate. Since 1968 the price of gold on the open market has widely fluctuated reaching $620/troy oz. in January 1980 but later dropped to $410/troy oz by January 1990.
Because of its use as a reserve store of value, the possession of gold is sometimes restricted or banned. Within the United States, the private possession of gold except as jewelry and coin collecting was banned between 1933 and 1975.
As an investment gold is not highly regarded in normal times, because it pays no dividends. However, gold becomes desirable in times of extremely weak confidence and during hyperinflation because gold maintains its value even as all other investments become worthless.
Gold is extracted from ores through the use of cyanide, amalgam, and smelting. Refining of the metal is frequently accomplished by electrolysis. This metal occurs in sea water at 0.1 to 2 mg/ton depending sample location. However, there is no profitable method for recovering gold from sea water yet.
Although gold is important to industry and the arts, it also retains a unique status among all commodities as a long-term store of value. It has been estimated that all the gold in the world that has been refined could form a single cube 60 ft. on a side.
wikipedia.org dumped 2003-03-17 with terodump