Chemistry Class 7

2.  All the materials which we can see and
feel around us are known as ‘matter’
 Definition : Matter is anything which has mass,
occupies space and can be perceived by our
senses
 Examples : Water, A stone, air, A table, A glass
etc.,
WHAT IS MATTER?

3. MASS vs. WEIGHT
 Definition of mass : The quantity of matter that
a body contains is known as matter.
 Definition of weight : The force with which the
earth pulls a body towards itself is known as
weight.
 Mass never changes from place to place, but
weight does.

4. MATTER HAS MASS &
OCCUPIES SPACE
 This proves that matter has mass and
occupies space

5. AIR - A MATTER
 Yes, air is also a matter as it has mass
and occupies space

6. COMPOSITION OF MATTER
 Matter is made up of atoms and molecules
 Atoms and molecules exhibit all the properties
of matter
 Molecules are formed by the combination of
atoms
Difference between an atom and a molecule :
 Atoms may or may not have independent
existence but molecules have independent
existence.

7. CHARACTERISTICS OF MATTER
 The properties of matter can be explained
based on their characteristics

8. CHARACTERISTICS OF MATTER
1) Inter-particular/ inter-molecular space
2) Inter-particular/inter-molecular force of
attraction
3) Random motion

9. CHARACTERISTICS OF MATTER
INTER-PARTICULAR/ INTER-MOLECULAR SPACE :

10. CHARACTERISTICS OF MATTER
INTERPARTICULAR/INTERMOLECULAR FORCE OF
ATTRACTION :
Stretching of rubber band

11. CHARACTERISTICS OF MATTER
RANDOM MOTION :
Dust particles under sunlight

12. UPCOMING TOPICS …
 States of matter
 Properties of solids, liquids and gases
 Interconversion of states of matter