Page 1 - Lesson Notes

SAI INTERNATIONAL SCHOOL
Class - VI
Subject - Chemistry
Topic – Changes Around Us
Sub-Topic –Application of Contraction and Expansion
Lesson Notes

Expansion and Contraction:

 Different materials expand or contract at different rates at different temperatures.
 Materials expand on heating and contract on cooling.

 Expansion and contraction are physical changes as no new substances are formed.

 When the cause of heating or cooling is removed, the substances return to their original
state.

 Thus, expansion and contraction are reversible changes.
 The amount of expansion differs in solids, liquids, and gases.

 Gases expand more than liquids, and liquids expand more than the solids.

 Expansion is a process in which an object becomes bigger in size, on heating.
 Contraction is a process in which an object becomes smaller in size or shrinks, on

cooling.

1. Application of Contraction and Expansion in Solids:

 When substances expand or contract, the particles stay in the same size.

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