Page 1 - 3-Lesson Notes-Application of Contraction and Expansion

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.
➢ The expansion is due to the increased spaces between the particles.

➢ The particles in the solids vibrate more when it is heated and thus, resulting in

expansion.
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