Gold
| Atomic Number: | 79 |
| Symbol: | Au |
| Atomic weight: | 196.9665 |
| Discovery: | known since prehistoric time |
| Electron Configuration: | [Xe]6s14f145d10 |
| Word Origin: | Sanskrit Jval; Anglo-Saxon gold; meaning gold - also Latin aurum, shining dawn |
| Isotopes: | There are 18 isotopes of gold. Gold-198, with a half-life of 2.7 days, has been used to treat cancer and other illnesses. |
| Properties: | The melting point of gold is1064.43°C, boiling point is 3080°C, specific gravity is 18.88 (20°C), with a valence of 1 or 3. The melting point of gold is an assigned value, which serves as a calibration point for the International Temperature Scale and International Practical Temperature Scale. In mass, gold is a yellow-colored metal, although it may be black, ruby, or purple when finely divided. Gold is the most malleable and ductile metal. One ounce of gold can be beaten out to 300 ft2. Gold is a good conductor of electricity and heat. It is not affected by exposure to air or to most reagents. It is inert and a good reflector of infrared radiation. Gold is usually alloyed to increase its strength. Pure gold is measured in troy weight, but when gold is alloyed with other metals the term karat is used to express the amount of gold present. |
| Uses: | Gold is used in coinage and is the standard for many monetary systems. Gold is used for jewelry, dental work, plating, and reflectors. Chlorauric acid (HAuCl4) is used in photography for toning silver images. Disodium aurothiomalate, administered intramuscularly, is a treatment for arthritis. |
| Sources: | Gold is found as the free metal and in tellurides. It is widely distributed and almost always associated with pyrite or quartz. Gold is found in veins and in alluvial deposits. Gold occurs in sea water in the amount of 0.1 to 2 mg/ton, depending on the location of the sample. |
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