Реферат: Gold Essay Research Paper Name of element
Gold Essay, Research Paper
Name of element: Gold (AU)Atomic Number: 79Atomic Mass: 196.9665Group in Periodic Table: IBDensity at 68.: 18.88Date Discovered and Who Discovered it: Gold was discovered around 3000 BC to 1200 BC. Gold probably was found on the ground and used by prehistoric man as a tool. Highly sophisticated gold art objects and jewelry discovered by archaeologists in the Royal Tombs at Ur, in what is now Southern Iraq, date back to around 3000 BC. Similarly, goldsmiths of the Chavin civilization in Peru were making ornaments by hammering and embossing gold by 1200 BC. Where and abundance in nature: Since gold is both durable and carefully guarded, most of the gold that has been taken from the Earth still exists. Much of it has been buried again in underground vaults, where it is held in government monetary reserves. In 1990 the bullion reserves of the free world were estimated to total some 43,000 tons. Of this, the United States held 11 percent. Gold reserves of South Africa were estimated at some 20,000 tons. Despite the prevalence of antihoarding laws, another 50,000 tons were believed to be privately held. People are willing to take enormous risks and short-term financial losses to hoard gold against the possibility of fiscal inflation. The rest of the world’s accumulated gold was held in official stocks by central banks or was industrially employed or lost. Today gold may be bought and sold on many markets. The largest is in London, England. Others exist in several nations of continental Europe, in the Middle East, and in Asia.
Past and Current use: Gold probably was found on the ground and used by prehistoric man as a tool. Highly sophisticated gold art objects and jewelry discovered by archaeologists in the Royal Tombs at Ur, in what is now Southern Iraq, date back to around 3000 BC. Similarly, goldsmiths of the Chavin civilization in Peru were making ornaments by hammering and embossing gold by 1200 BC. Gold is usually alloyed in jewelry to give it more strength, and the term carat describes the amount of gold present (24 carats is pure gold). It is estimated that all the gold in the world, so far refined, could be placed in a single cube 60 ft. on a side. It is metallic, with a yellow color when in a mass, but when finely divided it may be black, ruby, or purple. It is the most malleable and ductile metal; 1 ounce (28 g) of gold can be beaten out to 300 square feet. It is a soft metal and is usually alloyed to give it more strength… Gold’s superior electrical conductivity, its malleability and resistance to corrosion have made it vital to the manufacture of components used throughout a wide range of electronic products and equipment including computers telephones and home appliances. Gold has extraordinarily high reflective powers that are relied upon in the shielding that protects spacecrafts and satellites from solar radiation and in industrial and medical lasers that use gold-coated reflectors to focus light energy. And because gold is biologically inactive, it has become a vital tool for medical research and is even used in the direct treatment of arthritis and other intractable diseases.