Matter & its composition - I

Chemistry Class 7

1. MATTER AND ITS COMPOSITION

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. MASS vs. WEIGHT

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 IS AIR A MATTER? DOES IT HAVE 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 Inter-particular/ inter-molecular space Inter-particular/inter-molecular force of attraction Random motion

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

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