Gold is one of the most precious elements that exist in nature. The chemical symbol of gold is Au, derived from the Latin word ‘Aurum’. The atomic number gold is 79 and its atomic weight is 196.967 . The physical properties refer to the characteristics possessed by gold in its elemental form. The list of physical properties includes color, odor, hardness, boiling point, melting point, luster, density and many others. Gold is bright yellow in color and has a shiny and lustrous glow. The metal is softer in nature; however, it hardens after alloying with silver, copper and other metals. The boiling point of gold is 2970oC, while its melting point is 1064oC . Gold has a specific gravity of 19.3, which means gold is 19.3 times heavier than water. Gold is solid at room temperature. It is ductile in nature due to which it forms thin wires upon beating. It is the most malleable metal and flexible metal.
Gold is a good conductor of electricity. The metal is soluble in chloride solutions at higher temperatures. It is dense in nature and holds a density of 19300 kg/m3. Gold possesses a tensile strength of 120 MPa. It is a noble metal. Under normal conditions, gold is stable in air and water. It is extremely resistant to chemical reactions. Gold reacts with halogens to form trihalides. A mixture of aqua regia, consisting of hydrochloric and nitric acids has the ability to dissolve gold . The common alloys of gold are silver and platinum. Gold is the most electronegative metal and possesses a significant electron affinity. Au (I), Au (III) and Au (V) are the most common oxidation states of gold . Gold is radioactive in nature and has a stable isotope 197Au. The price of gold in CAD is $42.28 per gram .
Gold is available in nature in different types of rocks and geological environments. It is one of the scarce metals; however, it is available in two forms of commercial deposits, namely, lode and placer. While lode refers to primary deposits, placer refers to secondary deposits. Extraction of gold is possible from mineralizing solutions. Geologists support the hypothesis that the gold deposits found in the sedimentary and volcanic rocks are a result of circulating ground waters derived from magma about 2-5 miles beneath the earth’s surface . Gold is also available in the sea water at 0.1 to 2 mg per ton depending upon the location of extraction. A major supply of gold to the world is available from the countries of China, Australia, United States, Russia, South Africa, Peru, Canada and Indonesia .
In Canada, the largest deposits of gold are available at Cochrane, Red Lake, Kirkland Lake, Porcupine and Larder Lake in Ontario followed by the Canadian Shield in British Columbia and Nunavut in Newfoundland . Eastern Townships of Quebec are also higher in gold deposits. A major part of the gold production from Canada is available from underground hard rocks and pit mines. The rest of it is available from placer mining and base-metal mines. According to the statistics, the annual production of gold in the world is 80 million troy ounces per year. Extraction of gold takes place through the processes of amalgamation, smelting and cyanidation . The refining of gold is possible through the process of electrolysis.
The special properties possessed by gold makes it one of the most usable metals. Due to the malleable property of gold and its ability to withstand corrosion, the metal when mixed with alloys finds its use in the jewelry industry in the manufacture of ornaments . Gold alloy catalysts find their use in the production of glue and paints due to their potential of removing nitrogen oxide from diesel exhausts. The reflective property of gold makes it ideal in the use of space shuttles. Gold sunglasses protect the astronauts from the direct reflection of sunlight. Also, the windows in the cockpits of airplanes have a thin coat of gold to prevent the harmful sunrays . The use of gold on the windows of buildings helps to reflect heat in summer and retain the same in winter.
The property of electrical conductivity of gold makes it ideal for use in electronic appliances, such as mobile phones, television, microwave and many others. Circuit sockets, cable terminals and circuit boards have gold as the common substance . Several CDs and DVDs have minute amounts of gold in their construction. Gold connectors are a major use in the cars, in the form of anti-lock braking systems, crash sensors, ignition control electrics and electronic fuel injectors. The malleability and ductility of gold finds its use in the medicine industry. Gold injections help to relieve rheumatic pain. The resistance of gold to infection makes it the best for implants. Wires to pacemakers, stents and inner ear implants contain gold in them . Gold dust in a tablet form relieves depression and fatigue.
The use of gold in the treatment of cancers is in the trial phase. Gold is also available in the form of microchips filled with drugs. In dentistry, golden teeth enable the restoration process of teeth in the form of bridges and crowns . Gold finds its use in the clothing industry in the form of threads used for embroidery. In photography, gold helps to tone the silver image. Gold flakes find their presence in drinks and gourmet sweets, especially in the country of India. Gold nanoparticles find their use in the nanotechnology industry. Colloidal gold is a substitute for biological applications. Gold medals and trophies are an honor for winners in several competitions. Thus, gold is one of the valuable metals of nature, which serves various purposes in several fields.
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