Materials: Metals and Non-metals
Science Class Eight
Reaction of Non-metals with Oxygen
Reaction of Sulphur non-metal with Oxygen
When sulphur is burnt in air, it gives sulphur dioxide.
Sulphur (S) + Oxygen (O2) ⟶ Sulphur dioxide (SO2)
When sulphur dioxide is mixed with water it gives sulphurus acid.
Sulphur dioxide (SO2) + Water (H2) ⟶ Sulphurus acid (H2SO3)
Since, sulphurus acid is an acid, thus it turns blue litmus paper into red.
Nature of Non-metal Oxides
Oxides of non-metals are generally acidic in nature.
Reaction of Phosphorous, a non-metal with Oxygen
When phosphorous, a non-metal is left in the air, it catches fire and forms oxide of phosphorous.
Since, phosphorous is highly reactive with oxygen, thus it is stored in water.
Reaction of Non-metals with Water
Generally non-metals do not react with water.
Reaction of Non-metals with Acid
Generally non-metals do not react with acid.
Reaction of Non-metals with base
Non-metals react with base, but these reactions are more complex and will be taught in higher classes.
Displacement Reaction
Displacement of less reactive metal from its compound by a more reactive metal is called Displacement Reaction.
Example
Reaction of zinc metal with aqueous solution of Copper sulpahte
When Zinc metal reacts with aqueous solution of copper sulphate, zinc sulphate is formed.
Copper Sulphate (CuSO4) + Zinc (Zn) ⟶ Zinc sulphate (ZnSO4) + Copper (Cu)
In this reaction zinc is more reactive metal than copper. Thus, zinc replaces copper metal from the solution of copper sulphate.
Reaction of nails of Iron metal with aqueous solution of Copper sulpahte
When iron nails react with aqueous solution of copper sulphate, iron metal replaces copper from its aqueous solution and forms iron sulphate.
Copper Sulphate (CuSO4) + Iron (Fe) ⟶ Iron sulphate (FeSO4) + Copper (Cu)
In this reaction iron is more reactive metal than copper. Thus, iron replaces copper metal from the solution of copper sulphate.
Reaction of copper metal with the aqueous solution of zinc sulphate
When copper turnings are put in the aqueous solution of zinc sulphate, no reaction takes place.
Zinc sulphate (ZnSO4) + Copper (Cu) 𘞆 No reaction
Since, copper is less reactive than zinc metal, thus copper does not replace zinc metal from the aqueous solution of copper sulphate.
Use of Metals and Non-metals
Some Uses of Metals
(a) Metal like iron is used in making of ships, aeroplanes, wagons, rail lines, garters, etc. Iron is used in making of iron rods also. This is because iron is very hard and malleable.
(b) Metals like copper and aluminium is used in making of electric wires, because metals are good conductor of electricity.
(c) Copper, aluminium and iron metals are used in making of cooking utensils. This is because metals are good conductor of heat and can be beaten to a thin sheet, i.e. metals are malleable.
(d) Silver and gold metals are used in making of jewelry. This is because metals are malleable and ductile, and have shiny surface.
Some Uses of Non-metals
(a) Non-metal is essential for our life. Oxygen is a non-metal and is inhaled by all living beings during brething.
(b) Non-metals like nitrogen, is used in fertilizers to enhance the growth of plants, i.e. fertility of soil.
(c) Non-metals like carbon is used in water purification process.
(e) Non-metals, such as iodine is used in the purple coloured solution which is applied on wounds as an antiseptic.
(f) Non-metals, such as sulphur and phosphorous is used in crackers.
(g) Non-metals like phosphorous is used in match sticks and match boxes.
Summary
(1) Classification of Materials
On the basis of physical and chemical properties materials are classified into two groups. (a) Metal and (b) Non-metal
(2) Physical properties of metals and non metals
(a) Metals are generally hard, malleable, ductile, sonorous, lustrous, good conductors of heat and electricity and have high melting and boiling points.
(b) While non-metals are generally soft, non-malleable, non-ductile, non-sonorous, non-lustrous, bad conductors of heat and electricity and have low melting and boiling points.
Exceptions of metals and non-metals
(a) Metals are generally hard, but sodium and lithium metals are soft. Sodium is so soft that it can be cut using a knife easily.
(b) Metals are solid. But mercury is a metal which is liquid at room temperature. Mercury is an exception.
(c) Non-metals are not hard. But diamond, which is a form of non-metal carbon, is most hard naturally occurring material.
(c) Non-metals are dull in appearance. But graphite which is a form of non-metal carbon, has shiny surface.
(d) Iodine is a non metal and is shiny in appearance.
(e) Non-metals are bad conductor of electricity. But graphite, which is a form of non-metal carbon, is very good conductor of electricity.
Chemical Properties of Metals and Non-metals
Reaction of metals and non-metals with oxygen
Most of the metals form respective metal oxides when react with oxygen.
Metal + Oxygen ⟶ Metal Oxide
Most of the non metals form respective non-metal oxides when react with oxygen.
Non-metal + Oxygen ⟶ Non-metal Oxide
Nature of metal and non-metal oxides
Metal oxides are basic in nature, while non-metal oxides are acidic in nature.
Reaction of metals and non-metals with Water
Some metal forms respective metal hydroxide after reaction with water. Some metals like lead, copper, silver and gold do not react with water. But when copper is exposed to air for long time a greenish thin layer of mixture of copper hydroxide and copper carbonate is deposited over it.
Generally non-metals do not react with water.
Reaction of metals and non-metals with Acid
Metals produce hydrogen gas when react with an acid.
Generally non-metals do not react with acid.
Reaction of metals and non-metals with Base
Metals produce hydrogen gas when react with a base.
Non-metals also react with base, but reactions are more complex and is taught in higher classes.
Displacement Reaction
Displacement of less reactive metal from its compound by a more reactive metal is called Displacement Reaction.
In other words, when a more reactive metal reacts with a compound of less reactive metal, it displaces the less reactive metal with its compound.
Use of Metals and Non-metals
Some Uses of Metals
(a) Metal like iron is used in making of ships, aeroplanes, wagons, rail lines, garters, etc. Iron is used in making of iron rods also. This is because iron is very hard and malleable.
(b) Metals like copper and aluminium is used in making of electric wires, because metals are good conductor of electricity.
(c) Copper, aluminium and iron metals are used in making of cooking utensils. This is because metals are good conductor of heat and can be beaten to a thin sheet, i.e. metals are malleable.
(d) Silver and gold metals are used in making of jewelry. This is because metals are malleable and ductile, and have shiny surface.
Some Uses of Non-metals
(a) Non-metal is essential for our life. Oxygen is a non-metal and is inhaled by all living beings during brething.
(b) Non-metals like nitrogen, is used in fertilizers to enhance the growth of plants, i.e. fertility of soil.
(c) Non-metals like carbon is used in water purification process.
(e) Non-metals, such as iodine is used in the purple coloured solution which is applied on wounds as an antiseptic.
(f) Non-metals, such as sulphur and phosphorous is used in crackers.
(g) Non-metals like phosphorous is used in match sticks and match boxes.
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