Question

Definition of contraction and expansion in chemistry

Answer 1

Expansion and contraction. Substances expand or get bigger when they are heated up. They contract or get smaller when they are cooled down. This property can be useful. Thermometers work because the liquid inside them expands and rises up the tube when it gets hotter.

Answer 2

Substances expand (increase in size) when they get warmer, and they contract (decrease in size) when they get cooler. This property can be useful. For example: Thermometers work because the liquid inside them expands and rises up the tube when it gets hotter.