Gold: Royalty among the Elements
Gold has been known since prehistoric times, and is mined on all continents except Antarctica. It has been highly valued and treasured ever since its prehistoric discovery. Because of its relative rarity (it is the 75th most common element) and usefulness, it has been expensive to own. Because of this high value, it is a sign of wealth and often of royalty.
The modern English word “gold” comes from the Old English/Anglo-Saxon word “geolu,” meaning “yellow.” The symbol for elemental gold, Au, comes from the Latin word for gold, “aurum.” Aurum means “shining dawn,” an appropriate name for this glowing metal. Gold does not rust or tarnish.
Gold has an atomic number of 79, meaning that it has 79 protons in the nucleus and 79 electrons orbiting around the nucleus. Looking at the atomic weight of 196.9665 (rounded off to 197) shows that the most stable of gold’s 18 isotopes has 118 neutrons. One of the isotopes of gold, Gold-198, has a half-life of 2.7 days and has been used in medical treatment of cancer.
Pure gold is a soft metal. It is the most malleable and ductile of all metals. One ounce of gold can be beaten into a thin sheet covering 300 square feet. It is an excellent conductor of both heat and electricity, and also reflects infrared radiation. The finest gold thread possible to make is five (5) microns. If all the gold ever produced were to be made into a gold thread of 5 microns in diameter, it would circle the earth in the neighborhood of 7,200,000 times.
Gold melts at 1337.58 degrees Kelvin (1947.97 degrees Fahrenheit/1064.43 degrees Celsius) and boils at 3080.15 degrees Kelvin (5084.6 degrees Fahrenheit/2807 degrees Celsius).
Because gold is such a soft metal, it is normally alloyed with other materials to make it harder and stronger. Gold is used in jewelry, coinage, artwork (including statues), medicine (including dentistry), and in technology (including in lasers, computers and cell phones).
Gold jewelry that is not “gold-colored” has been mixed with any of various other metals. White gold is formed by adding either nickel or palladium. Copper will give a pink or rose color to gold. Silver added to gold will give a color of green. Purple gold can be made by adding aluminum. Blue gold comes from a combination of gold and indium.
Powdered gold loses the gold color, and is black. Rhodium, ruthenium, cobalt, chromium or carbon can be used in combination with gold to give it a black color as well.
The total amount of gold that has been produced through the fall of 2009 is estimated at 164,766 tons.
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