Page 43 - Science Class 08
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But if copper fillings are put into solu ons of v Atoms of metals can join together to form
iron sulphate, zinc sulphate and magnesium their crystals.
sulphate, no replacement reac on will take v Metals are used to make coins. These
place. The reason is that copper is less ac ve metals are copper, zinc and nickel.
than iron, zinc and magnesium. Remember v Metals like gold and silver are beaten into
that less reac ve metals cannot replace more foils that are used on sweets and as tonics.
ac ve metals.
Foils of aluminium are used for packing
food, medicines and chocolates.
Given below is a list of metals wri en in the
v Sodium is a component of common salt
order of increasing reac vity:
(sodium chloride). We use it in the kitchen
v Gold v Silver
for taste, in freezing mixtures to make
v Copper v Lead candies and as a raw material in industry.
v Iron v Zinc v Cement, a very useful material, has small
v Aluminium v Magnesium quan es of iron oxide, calcium oxide,
v Sodium v Potassium aluminium oxide and silicon dioxide as its
cons tuents. When mixed with water,
USES OF METALS
these react with it to form concrete.
v Metals have been in use since very early
v Metals are used to make cooking utensils.
mes. They have been used for various
v Copper is used in electrical wiring. Gold
purposes. Pure metals like gold, silver and
copper have been in use for ornaments, and silver are used for fine electrical
contacts in computers and solar cells.
utensils and jewellery since 3500 BC.
v Metals like iron and steel are very strong, v Shining metals like silver are highly
hard as well as rigid. So, they have been in reflec ng as they can reflect 90% light
falling on it. So, they are used as mirrors.
use for making buildings, bridges and
machines over the centuries. Vehicles like CORROSION
trains, satellites and industrial gadgets are Corrosion is a process where the metal
also made of steel. Iron is indeed the most corrodes. Corrosion is a natural process and in
important and useful metal. Aluminium is the presence of a moist atmosphere, chemically
another very strong metal widely used, ac ve metals get corroded.
especially in making aeroplanes.
v Some metals are useful to plants and
animals, though in very small quan es.
Iron and calcium are chief among them.
Iron is useful for blood-cells while calcium
for bones and teeth.
v Most metals are good. conductors as their
electrons can conduct heat and electricity
more easily than those of non-metals.
Corrosion
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