PPT - Materials:Metals & Non-Metals Class 8 Notes | EduRev

Science Class 8

Created by: Dr Manju Sen

Class 8 : PPT - Materials:Metals & Non-Metals Class 8 Notes | EduRev

 Page 1


CHAPTER - 4 
 
MATERIALS : METALS  AND  
NON  METALS 
Page 2


CHAPTER - 4 
 
MATERIALS : METALS  AND  
NON  METALS 
1) Occurrence of metals and non metals :- 
• Out of the 92 naturally occuring elements 70 
are metals and about 22 are nonmetals. 
Some elements show properties of both 
metals and non metals. They are called 
metalloids. 
• Only some metals like gold, silver, platinum 
etc are found in the free state. Most metals 
are found in the combined states as oxides, 
sulphides, carbonates, silicates etc. 
• Some non metals are found in the free state 
like helium, neon, argon etc. and some are 
found in free and combined states like 
sulphur, phosphorus etc.  
Page 3


CHAPTER - 4 
 
MATERIALS : METALS  AND  
NON  METALS 
1) Occurrence of metals and non metals :- 
• Out of the 92 naturally occuring elements 70 
are metals and about 22 are nonmetals. 
Some elements show properties of both 
metals and non metals. They are called 
metalloids. 
• Only some metals like gold, silver, platinum 
etc are found in the free state. Most metals 
are found in the combined states as oxides, 
sulphides, carbonates, silicates etc. 
• Some non metals are found in the free state 
like helium, neon, argon etc. and some are 
found in free and combined states like 
sulphur, phosphorus etc.  
2) Metallurgy :- 
• Metallurgy:- is science of extraction of metals from their 
ores and their purification. 
• Minerals:- are naturally occuring substances containing 
one or more elements or their compounds. 
• Ore:- is a mineral from which one or more metals can be 
extracted profitably. 
• Metallurgical processes:- consists of three main steps. 
They are :-    i) Concentration of the ore ii)  Reduction    
iii) Refining  
• Concentration of the ore:- is the removal of impurities 
from the ore. 
• Reduction:- the process of obtaining the metal from its 
compound. 
• Refining:- is the process of purification of the impure 
metals to obtain the pure metal. 
Page 4


CHAPTER - 4 
 
MATERIALS : METALS  AND  
NON  METALS 
1) Occurrence of metals and non metals :- 
• Out of the 92 naturally occuring elements 70 
are metals and about 22 are nonmetals. 
Some elements show properties of both 
metals and non metals. They are called 
metalloids. 
• Only some metals like gold, silver, platinum 
etc are found in the free state. Most metals 
are found in the combined states as oxides, 
sulphides, carbonates, silicates etc. 
• Some non metals are found in the free state 
like helium, neon, argon etc. and some are 
found in free and combined states like 
sulphur, phosphorus etc.  
2) Metallurgy :- 
• Metallurgy:- is science of extraction of metals from their 
ores and their purification. 
• Minerals:- are naturally occuring substances containing 
one or more elements or their compounds. 
• Ore:- is a mineral from which one or more metals can be 
extracted profitably. 
• Metallurgical processes:- consists of three main steps. 
They are :-    i) Concentration of the ore ii)  Reduction    
iii) Refining  
• Concentration of the ore:- is the removal of impurities 
from the ore. 
• Reduction:- the process of obtaining the metal from its 
compound. 
• Refining:- is the process of purification of the impure 
metals to obtain the pure metal. 
3) Physical properties of metals and non metals :- 
• Metals 
• Metals are solids (except 
mercury). 
 
• Metals are hard (except sodium, 
potassium etc. 
• Metals have metallic lustre. 
 
• Metals have high melting points 
and boliling points. 
• Metals are malleable ( can be 
made into thin sheets). 
• Metals are ductile (can be made 
into thin wires). 
• Metals are good conductors of 
heat and electricity. 
 
• Metals are sonorus (produces 
sound). 
• Non metals 
• Non metals may be solids, 
liquids or gases. 
 
• Non metals which are solids are 
brittle (diamond is the hardest). 
• Non metals do not have lustre 
some have a dull luster.  
• Non metals have low melting 
points. 
• Non metals are not malleable. 
 
• Non metals are not ductile. 
 
• Non metals are bad conductors 
of heat and electricity (except 
graphite). 
• Non metals are not sonorus. 
 
Page 5


CHAPTER - 4 
 
MATERIALS : METALS  AND  
NON  METALS 
1) Occurrence of metals and non metals :- 
• Out of the 92 naturally occuring elements 70 
are metals and about 22 are nonmetals. 
Some elements show properties of both 
metals and non metals. They are called 
metalloids. 
• Only some metals like gold, silver, platinum 
etc are found in the free state. Most metals 
are found in the combined states as oxides, 
sulphides, carbonates, silicates etc. 
• Some non metals are found in the free state 
like helium, neon, argon etc. and some are 
found in free and combined states like 
sulphur, phosphorus etc.  
2) Metallurgy :- 
• Metallurgy:- is science of extraction of metals from their 
ores and their purification. 
• Minerals:- are naturally occuring substances containing 
one or more elements or their compounds. 
• Ore:- is a mineral from which one or more metals can be 
extracted profitably. 
• Metallurgical processes:- consists of three main steps. 
They are :-    i) Concentration of the ore ii)  Reduction    
iii) Refining  
• Concentration of the ore:- is the removal of impurities 
from the ore. 
• Reduction:- the process of obtaining the metal from its 
compound. 
• Refining:- is the process of purification of the impure 
metals to obtain the pure metal. 
3) Physical properties of metals and non metals :- 
• Metals 
• Metals are solids (except 
mercury). 
 
• Metals are hard (except sodium, 
potassium etc. 
• Metals have metallic lustre. 
 
• Metals have high melting points 
and boliling points. 
• Metals are malleable ( can be 
made into thin sheets). 
• Metals are ductile (can be made 
into thin wires). 
• Metals are good conductors of 
heat and electricity. 
 
• Metals are sonorus (produces 
sound). 
• Non metals 
• Non metals may be solids, 
liquids or gases. 
 
• Non metals which are solids are 
brittle (diamond is the hardest). 
• Non metals do not have lustre 
some have a dull luster.  
• Non metals have low melting 
points. 
• Non metals are not malleable. 
 
• Non metals are not ductile. 
 
• Non metals are bad conductors 
of heat and electricity (except 
graphite). 
• Non metals are not sonorus. 
 
4) Chemical properties of metals and non metals :- 
a) Reaction with oxygen :- 
     Metals react with oxygen to form metallic oxides. These oxides are    
    basic oxides because they react with water to form bases. 
    Eg. Magnesium burns in air to form magnesium oxide. Magnesium  
    reacts with water to form magnesium hydroxide. 
            2 Mg + O
2
                2 MgO 
              MgO + H
2
O                Mg(OH)
2  
      
Non metals react with oxygen to form non metallic oxides. These  
   oxides are acidic oxides because they react with water to form    
   acids. 
   Eg. Sulphur burns in air to form sulphur dioxide. Sulphur dioxide  
   reacts with water to form sulphurous acid. 
               S + O
2
                  SO
2
  
              SO
2
 + H
2
O                 H
2
SO
3 
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