Page 5 - Curriculum Visions Dynamic Book

Silver
Silver is a white, shiny, heavy metal. Its symbol is Ag, after argentum,
a Latin word meaning “white and shining”. Silver has been sought after since the earliest times and is regarded as a precious metal, just as gems are precious stones. Yet although silver is known for its precious value, only 16% of all the silver used in the world is used for coins and jewellery, while 40% goes to make photographic film. Much of the rest is used in industry and health services. Mirrors for example,
are mostly made by silvering the back of glass.
Gold
The chemical symbol for gold is Au, after the Latin word for gold, aurum. Gold is one of the rarest elements found on Earth and has been sought out by people since ancient times. One of the reasons for this is that it
is a soft metal that nearly always occurs in pure, or native, form. Ancient peoples could thus make use of gold along with silver and copper without special tools and without refining.
Most of the world’s gold is in sea water, where it is too dispersed to be collected. On land it is found in veins and in small fragments
in river beds and coastal sands. Its discovery has set off many gold rushes throughout the world.
Gold resists corrosion better than almost any other material. It does not tarnish, but remains a bright, lustrous, deep yellow colour indefinitely. In fact this resistance
to corrosion has made the metal vital in the electronics industry, where
it is used, for example, to make electrical contacts.
 An untarnished one-cent coin. Most copper-coloured coins are made from an alloy of copper, tin and zinc. Many of the silver-coloured coins we use today are an alloy of copper and nickel.
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