INTRODUCTION

• A METAL is a material that is typically hard ,shiny ,has good electrical and thermal conductivity.

• Metals are generally malleable , fusible and ductile.

• About 91 of the 118 elements in the periodic table are metals.

CONT..

• Gold is one of the few elements that can affect politics and economics. Wars have been fought over access to gold.

• Many nations still count their wealth according to the amount of gold they keep in storage.

• Large amounts of gold are still used in the manufacture of coins, medals, jewelry, and art. Gold also has a number of uses in industry, medicine, and other applications. For example, one radioactive isotope of gold is commonly used to treat cancer.

GOLD

• Symbol : Au

• Atomic Number : 79

• Melting point : 1064.18”c

• Color : yellow or golden

• Crystal structure : FCC

• Family : Group 11 (IB) ,Transition metal

HISTORY OF GOLD

• Gold is discovered by James W. Marshall.

• He had discovered gold unexpectedly while overseeing construction of a sawmill on the American River on January 24, 1848 in california.

GOLD CONT..

• The element symbol for gold is Au. The symbol comes from the old Latin name for gold, aurum, which means "shining dawn" or "glow of sunrise".

• One of the special skills developed by the Egyptians was the adding of gold to glass objects. They found a way to use gold to make glass a beautiful ruby-red color. The glass became known as gold ruby glass.

• Gold is also mentioned in a number of places in the Bible.

FACTS CONT..

• Gold is also used in medicine. The radioactive gold isotope Au -198 can destroy tumor cells in the body.

• In the United states. Thousands of people flocked to California in search of gold. This era was called the Gold Rush. People became very rich.

GOLD IN SPACE ..

• The James Webb Space Telescope is the first most advanced teli scope ever build by NASA.

• The hexagons are coated with a thin layer of gold because the element is the best reflector of infrared light, the wavelength that marks extremely far-off objects.

• And it gives wonderful information of universe.

EFFECT ON CIVILIZATION

• Gold has been called the most beautiful of all chemical elements.

• Its beauty has made it desirable for use in jewelry, coins, and

artwork for thousands of years.

• It was one of the first pure metals to be used by humans.

FACTS CONT …

• The gold blocks harmful ultraviolet rays from the sun.

• The world's largest gold crystal is the size of a golf ball and comes from Venezuela. The 7.7-ounce (217.78 grams) crystal is worth about $1.5 million.

• Earthquakes can create gold.

• You can eat gold … if you really want to.

Don't fear for your stomach: The gold isn't digested and just passes right through, according to Edible Gold, a company that sells gold leaf.

PHYSICAL PROPERTIES

• Gold is both ductile and malleable.

• Two other important properties are its reflectivity and lack of electrical resistance.

• Gold is extremely ductile. 28 grams of gold can be stretched into a gold thread 8 kilometers long . The sheet will be only 0.00025 centimeters (one ten-thousandth of an inch) thick.

CHEMICAL PROPERTIES

• Generally speaking, gold is not very reactive.

• do not corrode (rust) or tarnish very easily.

• It don’t dissolve with acids.

• It cannot combine with oxygen and other gases.

OCCURRENCE IN NATURE

• Gold occurs in nature in both its free state and in compounds

• The most common compounds of gold are the tellurides. A telluride is a compound of the element tellurium result gold telluride (AuTe2).

• About 1/4 of the world's gold comes from South Africa. Other leading producers of the metal are the United States, Australia, Canada, China, and Russia.

• In the United States, about 3/4 of the Nevada ,California, Montana, Alaska ,and South Dakota also produce gold.

EXTRACTION OF GOLD

• There are two ways to remove gold from it’s ores.

• One is mixed an ore with Mercury metal . mercury combines with gold in the ore to form an amalgam.

• Gold ore + Mercury Amalgam.

• Amalgam is a mixture of two are more metals .

one of the metal is Mercury.

• Finally gold amalgam is removed from the ore .

• Gold amalgam Pure Gold ( heated up to mercury drive off ).

MEASUREMENTS

1 karat = 1/5 of a gram = 200 milligrams

KARAT GOLD CONTENT

24 karat 99.95+ %

22 karat 91.6 %

21 karat 87.5 %

20 karat 83.3 %

18 karat 75 %

15 karat 62.5 %

10 katat 41.7 %

USES

• In a 1986 study, experts estimated that 121,000 tons of gold had been mined throughout history.

• Of that amount, about 18,000 tons were used for

industrial, research and health.

• Of the remaining 103,000 tons of gold, about a third (35,000 tons) had been made into gold bars held by national banks.

• Finally, the remaining 68,000 tons of gold are owned by private individuals. This gold exists in the form of jewelry, coins, or bullion. Gold bullion are bars or other large pieces of pure gold.

USES CONT..

• Jewelry is the largest single use of gold. In 1996, about 3,290 tons of gold were made worldwide. Of that amount, nearly 85 percent was made into jewelry. The second largest use of gold (about 213 tons) was in industrial devices and consumer products.

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