CBSE Class 6 Science Chapter 6 Notes Changes Around Us
Changes Around Us Class 6 Notes Understanding the Lesson
1. An alteration in the physical or chemical properties of a matter due to the effect of some kind of energy is called a change.
2. The changes may affect the size, colour, shape and state of a body.
(i) Folding of paper-change in shape
(ii) Melting of ice-change in state
4. Almost everything in the surrounding undergoes some changes.
5. Effect of force, effect of heat, effect of reaction are the factors which make a thing to undergo a change.
6. Heating may cause the expansion of certain materials.
7. Changes can be classified into two types:
(i) Physical and chemical changes.
(ii) Reversible and irreversible changes.
8. A change in which property of a substance is not changed is called a physical change.
9. If a substance loses its identity during a change and gets converted into new substance with a new property, it is called a chemical change.
10. A change which can be reversed to its original state after removing its cause is called reversible change.
11. A change which cannot be reversed back to its original state, is termed as irreversible change.
Class 6 Science Chapter 6 Notes Important Terms
Changes: An alteration in the physical or chemical properties of a matter due to the effect of some kind of energy is called a change.
Contraction: A process in which an object becomes smaller or shrinks is called contraction.
Evaporation: The process in which liquid changes into vapour is called evaporation.
Expansion: The process in which an object becomes bigger in size is called expansion.
Melting: The process by which solid melts into liquid on heating is called melting.