Silver
Ag
Atomic No. - 47
Silver has been used for thousands of years for ornaments and
utensils, for trade, and as the basis for many monetary systems.
The History Says
Associated with the moon, as well as with the sea and various lunar
goddesses, silver was referred to by alchemists by the name luna. One
of the alchemical symbols for silver is a crescent moon with the open
part on the left.
The Present Scenario
In India, foods can be found decorated with a thin layer of silver,
known as 'Varak.'
Silver
is found in the earth as native silver, a mineral. It has a bright,
metallic luster. When it is untarnished, it has a white color. Silver
is usually found with a various different elements forming variety of
minerals and ores. In gold, lead, zinc, and copper ores, it is found
in a very small amounts, which is known as trace amount.
As a mineral, it crystallizes in the cubic (isometric) system. In a
very rare cases silver forms crystals. Generally, found in thin sheets
or as long wires and bundles of wires. Silver is soft with a hardness
on Mohs scale only at 2 to 3. It is malleable and ductile.
The name 'silver' was named from the Old English (Anglo-Saxon) word
'seolfer.' The word is also related to 'silber' in German and 'zilfer'
in Dutch. Earlier it was also called by a Latin name 'Luna.' It simply
means 'moon,' because of its bright luster. The symbol 'Ag' has been
taken from the Latin word for silver, 'Argentum.'
Physical Properties of Silver
| Cleavage |
None |
| Color |
Silver-white on untarnished
surface. Tarnishes dark yellow to black. |
| Hardness |
2.5-3 |
| Fracture |
Hackly |
| Specific Gravity |
9.6 - 12.0 (Pure = 10.5) |
| Luster |
Metallic |
| Streak |
Silver-white to light gray.
Streak shiny. |
| Transparency |
Opaque |
| Tenacity |
Ductile and Malleable |
Sources of Silver
Silver occur in lead, zinc, and copper ore deposits. Seventy-five
percent of the resources in the world are found in association with
other metal ores. The remaining is found with gold. The most important
ore mineral is argentite, Ag2S (silver sulfide).
Significant world silver producing countries are the US, Mexico,
Peru, Chile, and Canada. In the US, Nevada is leads in silver
producing. There it occurs as a by-product of gold mining.
Uses of Silver
- For
thousand of years silver has been used for jewelry and all types of
decorative items.
- It
is used in silverware.
- Silver
bromide and silver nitrate are used in photography.
- Silver
conducts electricity well, so it is used in electrical products.
- It
is used by dentists in amalgam fillings.
- It
is used in the production of bearings.
- As
untarnished silver is the best reflector of light, it was used in
ancient times to make mirrors.
- Sterling
silver, an alloy of other metal (usually copper), was used as
currency in the United States.
|
