PPT: Changes Around Us: Physical and Chemical | PPTs for Class 7 PDF Download

 Page 1


Physical and 
Chemical 
Changes
Page 2


Physical and 
Chemical 
Changes
Introduction
Everyday Changes
We notice many changes 
in our surroundings daily. 
These changes involve 
one or more substances.
Examples
Dissolving sugar in water, 
setting curd from milk, 
souring of milk, and 
stretching a rubber band.
Two Main Types
These changes can be grouped into physical changes 
and chemical changes.
Page 3


Physical and 
Chemical 
Changes
Introduction
Everyday Changes
We notice many changes 
in our surroundings daily. 
These changes involve 
one or more substances.
Examples
Dissolving sugar in water, 
setting curd from milk, 
souring of milk, and 
stretching a rubber band.
Two Main Types
These changes can be grouped into physical changes 
and chemical changes.
Physical Change
Definition
In a physical change, a substance undergoes 
changes only in its physical properties such 
as shape, size, colour and state, and no new 
substance is formed.
Examples
Heating of water, melting of butter, cutting of 
paper.
Page 4


Physical and 
Chemical 
Changes
Introduction
Everyday Changes
We notice many changes 
in our surroundings daily. 
These changes involve 
one or more substances.
Examples
Dissolving sugar in water, 
setting curd from milk, 
souring of milk, and 
stretching a rubber band.
Two Main Types
These changes can be grouped into physical changes 
and chemical changes.
Physical Change
Definition
In a physical change, a substance undergoes 
changes only in its physical properties such 
as shape, size, colour and state, and no new 
substance is formed.
Examples
Heating of water, melting of butter, cutting of 
paper.
Properties of 
Physical Changes
Temporary
The change can 
usually be 
reversed.
No New 
Substance
Only physical 
properties 
change, not 
chemical 
composition.
Energy 
Exchange
Energy forms 
like heat or light 
are neither 
emitted nor 
absorbed.
Page 5


Physical and 
Chemical 
Changes
Introduction
Everyday Changes
We notice many changes 
in our surroundings daily. 
These changes involve 
one or more substances.
Examples
Dissolving sugar in water, 
setting curd from milk, 
souring of milk, and 
stretching a rubber band.
Two Main Types
These changes can be grouped into physical changes 
and chemical changes.
Physical Change
Definition
In a physical change, a substance undergoes 
changes only in its physical properties such 
as shape, size, colour and state, and no new 
substance is formed.
Examples
Heating of water, melting of butter, cutting of 
paper.
Properties of 
Physical Changes
Temporary
The change can 
usually be 
reversed.
No New 
Substance
Only physical 
properties 
change, not 
chemical 
composition.
Energy 
Exchange
Energy forms 
like heat or light 
are neither 
emitted nor 
absorbed.
Chemical Change
Definition
Occurs when substances 
react to form new substances 
with different properties.
Examples
Food digestion, fruit ripening, 
grape fermentation.
Applications
Medicines, plastics, and 
detergents result from 
chemical reactions.