An alloy is a homogeneous mixture of two or more metals. It is prepared to improve the properties like corrosion resistance, malleability, ductility, tensile strength etc.,
They are prepared by melting two or more metals (or nonmetals)
in some required fixed proportion and allowing the molten product to cool at
room temperature.
Bronze is an alloy of copper zinc and tin in a ratio of
8:1:1. It can be better polished and used in making statues, coins and household utensils.
Stainless steel is an alloy of iron, carbon, chromium and
nickel. It does not rust and is unaffected by mild acids and alkalis. It is used
for making household utensils, cutlery, surgical instruments and ornamental
articles. Duralumin is an alloy of aluminium, copper, manganese and magnesium.
It is very hard, strong and has good tensile strength. It is
used for making aircraft frames, automobile components and household utensils.
Properties of nonmetals
They are generally gases at room temperature (Bromine is a
liquid while carbon, sulphur, phosphorus and silicon are solids).
They have low melting and boiling points.
They are not hard and are brittle.
Nonmetals have low density.
They are neither malleable nor ductile.
Nonmetals do not have lustre (except iodine and graphite)
They do not conduct electricity nor heat (amorphous carbon, and graphite are good conductors of electricity).
They lack tensile strength.
Properties and Uses of
some common nonmetals
Chlorine
Chlorine is a greenish-yellow gas with a pungent odour. It is a
poisonous gas and heavier than air. It is used for bleaching purposes by
converting into bleaching powder.
It is used for sterilization of water in the manufacture of
insecticides and pesticides like DDT and BHC. Iodine is a brownish, grey,
shining crystalline sublimable solid.
It is insoluble in water but soluble in alcohol, carbon
tetrachloride and potassium iodide solution in water. Sodium or potassium
iodide in small quantities with common salt is extremely essential for the proper
functioning of our human body. Silver iodide is used in making photographic
films.
Graphite
Graphite is a shining grey-coloured crystalline form of carbon. It is a good conductor of heat and electricity. It is used as pencil lead, electrodes, and dry lubricant, in nuclear reactors and in making heat-resistant crucibles.