Gold Au

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Gold (Au)
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The symbol for gold on the periodic table is Au.
Gold
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• The discoverer of gold is unknown.
• Although it is believed to have been discovered
  around 3000BC.
• This precious metal has been highly sought after
  for many centuries.
• Gold has the appearance of
• It is soft, dense, shiny and the most malleable
  and ductile of all metals known.
• Gold occurs as small nuggets or small grains
  which can be found in rocks.

Metallic Yellow
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• Melting point 1063 degrees Celsius
• Boiling point 2856 degrees Celsius
• Density 19.3 g cm-3
• Gold isnt very reactive.
• However, the look of its surface can be changed
  by chlorine, fluorine and cyanide.
• Mercury can dissolve Gold, but it doesnt react
  with it.

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• Coinage
• Jewellery
• Dental Work
• Plating
• Reflectors.
• It is a good conductor of heat and electricity,
  and because it doesnt tarnish when exposed to
  air gold can be used to make electrical
  conductors and printed circuit boards.
• Gold is also used to help shield spacecraft and
  skyscrapers from the suns heat because it is
  good at reflecting infrared radiation.

Uses for Gold
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Other Uses of Gold
Gold-198 is a radioactive isotope of gold. It is
used for treating cancer. Gold sodium
thiosulfate (AuNa3O6S4) is used for the treatment
of arthritis. Chlorauric acid (HAuCl4) is used
to preserve photographs by replacing the silver
atoms present in an image.
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Pure gold is referred to as 24 carat gold. It
is often alloyed with silver and copper. 24 carat
- 100 gold. 18 carat - 75 gold 25 silver
and/or copper. 9 carat - 37.5 gold 62.5
silver and/or copper.
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Major Steps in Extraction of Gold from its ore.
Froth Flotation
Host rock and specks of gold.
Concentrated gold ore.
Cyanide process
Add zinc or electrolysis
Au(CN)2- (aq)
Au
Extraction of Gold using Cyanide 4Au (s) 8CN-
(aq) 2H2O (l) O2 (g)
4Au(CN)2- (aq) 4OH- (aq)
The Au(CN)2- is separated from the pulp using
activated carbon. The gold is then recovered by
adding zinc (metal ion displacement) or by
electrolysis.
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Interesting Facts

• The most famous piece of gold is the face mask to
  the boy king of Egypt, Tutankhamun. Some of the
  greatest treasures of goldsmiths art was also
  found in his tomb.

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The properties of gold give it the ability to be
beaten into sheets no thicker than 0.00001 mm or
400 times thinner than a human hair. Or The
fact that gold is so malleable and ductile one
gram of it can be beaten into a one square metre
sheet.
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• In every ton of seawater 1 milligram of gold has
  been dissolved, but at the moment it currently
  costs more to extract the gold from this than
  what the gold is worth itself.
• There is about 120,000 to 140,000 tonnes of gold
  above ground.
• Imagine a solid gold cube about the size of a
  tennis court. This is the amount of of gold that
  has been produced.
• If this amount of was distributed to every person
  in the world, you would have only about 23 grams
  of gold.

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History of Gold
Since prehistoric times, gold has been known
about and highly valued. Gold is used to
symbolise purity, value and royalty. It is also a
sign of wealth. Gold can be found freely in
nature, however it is usually found in silver,
quartz, lead, zinc or copper.