Chapter 6 - Physical and Chemical changes - PPT, Science, class 7,CBSE PDF Download

 Page 1


CHAPTER - 6 
 
PHYSICAL AND CHEMICAL CHANGES 
Page 2


CHAPTER - 6 
 
PHYSICAL AND CHEMICAL CHANGES 
1) Changes around us :-  
   In our daily life we come across several changes. 
Eg :- 
- Dissolving sugar in water. 
- Formation of curd from milk. 
- Cooking of food.  
- Cutting of a piece of paper. 
- Stretching a rubber band. 
- Melting of ice. 
- Melting of wax 
- Boiling of water. 
- Rusting of iron. 
- Burning of candle  
- Burning of wood. 
- Burning of coal. 
Page 3


CHAPTER - 6 
 
PHYSICAL AND CHEMICAL CHANGES 
1) Changes around us :-  
   In our daily life we come across several changes. 
Eg :- 
- Dissolving sugar in water. 
- Formation of curd from milk. 
- Cooking of food.  
- Cutting of a piece of paper. 
- Stretching a rubber band. 
- Melting of ice. 
- Melting of wax 
- Boiling of water. 
- Rusting of iron. 
- Burning of candle  
- Burning of wood. 
- Burning of coal. 
2) Types of changes :- 
     Changes are of two main types. They are :- 
 i) Physical change 
ii) Chemical change 
    Physical change :- is a change in which no new 
substance is formed. 
    Chemical :- change is a change in which new substances 
are formed.  
Page 4


CHAPTER - 6 
 
PHYSICAL AND CHEMICAL CHANGES 
1) Changes around us :-  
   In our daily life we come across several changes. 
Eg :- 
- Dissolving sugar in water. 
- Formation of curd from milk. 
- Cooking of food.  
- Cutting of a piece of paper. 
- Stretching a rubber band. 
- Melting of ice. 
- Melting of wax 
- Boiling of water. 
- Rusting of iron. 
- Burning of candle  
- Burning of wood. 
- Burning of coal. 
2) Types of changes :- 
     Changes are of two main types. They are :- 
 i) Physical change 
ii) Chemical change 
    Physical change :- is a change in which no new 
substance is formed. 
    Chemical :- change is a change in which new substances 
are formed.  
3) Physical changes :- 
     Physical change is a change in which no new substance 
is formed. 
     In a physical change the physical properties like shape, 
size, state etc. of the substance changes. 
   Eg :- Cutting of paper into pieces, Melting of ice,            
            Boiling of water, Stretching a rubber band etc.  
     Some physical changes are reversible. 
   Eg :- Melting of ice, Boiling of water, Stretching a rubber  
            band etc. 
Page 5


CHAPTER - 6 
 
PHYSICAL AND CHEMICAL CHANGES 
1) Changes around us :-  
   In our daily life we come across several changes. 
Eg :- 
- Dissolving sugar in water. 
- Formation of curd from milk. 
- Cooking of food.  
- Cutting of a piece of paper. 
- Stretching a rubber band. 
- Melting of ice. 
- Melting of wax 
- Boiling of water. 
- Rusting of iron. 
- Burning of candle  
- Burning of wood. 
- Burning of coal. 
2) Types of changes :- 
     Changes are of two main types. They are :- 
 i) Physical change 
ii) Chemical change 
    Physical change :- is a change in which no new 
substance is formed. 
    Chemical :- change is a change in which new substances 
are formed.  
3) Physical changes :- 
     Physical change is a change in which no new substance 
is formed. 
     In a physical change the physical properties like shape, 
size, state etc. of the substance changes. 
   Eg :- Cutting of paper into pieces, Melting of ice,            
            Boiling of water, Stretching a rubber band etc.  
     Some physical changes are reversible. 
   Eg :- Melting of ice, Boiling of water, Stretching a rubber  
            band etc. 
4) Chemical changes :- 
    Chemical change is a change in which new substances are formed. 
     A chemical change is also called a chemical reaction. 
Eg :- Rusting of iron, Burning of wood, Formation of curd from milk,  
         Cooking of food etc.   
     During a chemical change the following changes take place :- 
  i) Formation of new substances. 
 ii) Heat or light may be absorbed or released. 
iii) Sound may be produced. 
iv) A colour change may take place. 
 v) A change in smell may take place. 
vi) A gas may be formed.