Gold is a bright yellow metal that occurs naturally in the earth. It has been used for over 5000 years for jewelry, currency and art due to its attractive color and resistance to corrosion. Gold is also used in electronics, dentistry and aerospace applications where its conductivity, malleability and resistance to corrosion are beneficial. It can also be used as a decorative ingredient in some foods and drinks.

2. DISCOVERED of GOLD
• Gold has been known since prehistoric times
and was one of the first metals to be worked,
mainly because it was to be found as nuggets
or as particles in the beds of streams.
• Gold artifacts dated to 5000 years ago have
been found in Egyptian tombs; gold was
already being beaten into sheets, foil and
wire in Egypt at this time.

5. PHYSICAL PROPERTIES OF
GOLD
• Gold is a chemical element with
symbol Au and atomic number 79.
• In its purest form, it is a bright,
slightly reddish yellow, dense,
soft, malleable and ductile metal.
• Chemically, gold is a transition
metal and a group 11 element.
• It is one of the least reactive
chemical elements, and is solid
under standard conditions.

6. PHYSICAL PROPERTIES OF
GOLD
• The metal therefore occurs often in
free elemental form, as nuggets or
grains, in rocks, in veins and
in alluvial deposits.
• It occurs in a solid solution series
with the native element silver and
also
naturally alloyed with copper and p
alladium.
• Less commonly, it occurs in
minerals as gold compounds, often
with tellurium

8. CHEMICAL PROPERTIES of
GOLD
• Gold resists attacks by individual acids,
but it can be dissolved by aqua regia.
• The acid mixture causes the formation of a
soluble gold tetrachloride anion.
• Gold metal also dissolves
in alkaline solutions of cyanide, which are
used in mining and electroplating.

9. CHEMICAL PROPERTIES of
GOLD
• It is insoluble in nitric acid, which
dissolves silver and base metals, a
property that has long been used
to refine gold and to confirm the presence
of gold in items, giving rise to the term acid
test; it dissolves in mercury, though,
forming amalgam alloys, but this is not
a chemical reaction.

10. CHEMICAL PROPERTIES of
GOLD
• Gold is unaffected by oxygen at any
temperature; similarly, it does not react with
ozone. Gold is strongly attacked by fluorine at
dull-red heat to form gold(III) fluoride.
• Gold does not react with sulfur
directly,but gold(III) sulfide can be made by
passing hydrogen sulfide through a dilute
solution of gold(III) chloride or chlorauric acid.

11. CHEMICAL PROPERTIES of
GOLD
• Gold readily dissolves in mercury at room temperature
to form an amalgam, and forms alloys with many other
metals at higher temperatures. These alloys can be
produced to modify the hardness and other
metallurgical properties, to control melting point or to
create exotic colors
• Common oxidation states of gold include +1and +3
.Gold ions in solution are
readily reduced and precipitated as metal by adding
any other metal as the reducing agent.
• The added metal is oxidized and dissolves, allowing
the gold to be displaced from solution and be
recovered as a solid precipitate

12. COLOR
• Most pure metals are gray or silvery white, gold is
slightly reddish yellow.
• This color is determined by the density of loosely
bound (valence) electrons; those electrons oscillate as
a collective "plasma" medium described in terms of
a quasiparticle called a plasmon.
• The frequency of these oscillations lies in the
ultraviolet range for most metals, but it falls into the
visible range for gold due to subtle relativistic
effects that affect the orbitals around gold atoms.
• Similar effects impart a golden hue to
metallic caesium.

13. • Common colored gold alloys
such as rose gold can be
created by the addition of
various amounts of copper and
silver, as indicated in the
triangular diagram to the right.
• Alloys containing palladium or
nickel are also important in
commercial jewelry as these
produce white gold alloys.
• Less commonly, addition
of manganese, aluminium, iron,
indium and other elements can
produce more unusual colors of
gold for various applications
COLOR

14. OCCURRENCE of GOLD
• Many pyrite and pyrhotite minerals contain
gold from which the metal is recovered during
the extraction
of copper, silver, lead, zinc and nickel.
• Although in low concentrations, gold is also
present in the sea water, being conservatively
estimated that the oceans contain 70 million
tons of gold in solution.
• The major world producers of gold are South
Africa, Canada, the United States and
Australia.

15. GOLD DEPOSITS
• Containing gold, sulphur
deposits
• The epithermal deposits
• Ultramafic rock deposits
• Gold containing skarns
• Updated placer gold
deposıts
• Including gold porphyria
deposits

18. USES FOR GOLD
• As a natural element, gold has many special
qualities that make it an important raw material in
a number of scientific applications.
• Besides it’s value to the jewelry, finance,and
refining industries, gold is also prized in:
-Dentistry
-Medicine
-Electronics
-Aerospace

19. Gold in Dentistry
• Gold is distincly useful to dentistry for two reasons:
-It’s very malleable and easy to work with.
-It’s completely inert to saliva and other body
chemistry
• These qualities make gold a perfect material to
build crowns and bridges that form to the unique
shape of teeth.
• Also, gold dental parts will never corrode and are
not harmful if swallowed.
-That’s why gold teeth are so common.

20. Gold in Medicine
• Chemical compounds made from
gold can be used to treat
inflammation.
• Gold sodium thiosulfate and gold
sodium thiomalate are used to
reduce stiffness and swelling
associated with rheumaotid
arthritis.
• - Gold compounds can be
administered either orally or via
instramuscular injection.
• The study of gold’s role as a
medicinal treatment is called
‘aurotherapy’

21. Gold in Electronics
• Gold is a top-notch electrical
conductor , so it’s used to
build capacitors and establish
electrical connections.
• -Gold is an important
component in nearly every
electrical device.
• Unlike copper and silver –
which are also prized for their
electrical conductivity- gold
never corrodes.
• -Electronic devices that use
gold tend to last much longer.

22. Gold in Aerospace
• Gold offers excellent protection
from electromagnetic radiation.
• -Astronaut helmets take
advantage of this protection by
coating the visor with a layer of
gold pounded so thin, it’s see-
through.
• The windshields of jets are also
use a see-through layer of gold
• -An electric current can be
passed through the gold-
infused windshield to instantly
clear away water, fog, and frost.

23. FOOD AND DRINK
• Gold can be used in food and has
the E number 175.
• Gold leaf, flake or dust is used on
and in some gourmet foods,
notably sweets and drinks as
decorative ingredient.
• Gold flake was used by the
nobility in medieval Europe as a
decoration in food and drinks, in
the form of leaf, flakes or dust,
either to demonstrate the host's
wealth or in the belief that
something that valuable and rare
must be beneficial for one's
health.

24. FOOD AND DRINK
• Since metallic
gold is inert to all
body chemistry, it
has no taste, it
provides no
nutrition, and it
leaves the body
unaltered.