Lesson Starter WRITE IN SENTENCES Describe what happens to the particles when you: a) Heat a liquid up b) Cool the substance back down

Lesson 8 – Learning Intention To learn what happens to solids when we heat them up

Aim of the experiment We know that particles move faster when we give them more energy (by heating them up) Does this make the material (being heated) change in any way?

Apparatus Goggles Bunsen burner Metal ball and ring (or clamp and T bar) Clamp stand

Method Use the clamp stand to hold the ring (or clamp) securely Check the ball fits through the ring (or the t-bar fits into the clamp) Light the Bunsen burner and turn it to the warmest flame CAREFULLY roast the ball (or T-bar) for 1 minute Now try and see if it still fits- BE CAREFUL Hold the metal under the cold tap for a few minutes Check to see if it fits Turn off the Bunsen and let everything cool down

Safety Roasting hot metal is very dangerous What safety precautions do we need to take?

What did you see? Why do you think this happened? Results What did you see? Why do you think this happened?

Conclusion When we heat the particles up, we gave them more energy so they moved further apart causing the material to get bigger This is called EXPANSION

Conclusion When we cooled the metal back down, the particles didn’t have as much energy so couldn’t spread out as much The material got smaller This is called CONTRACTION

Particles The particles themselves DO NOT CHANGE SIZE It is the space between them that gets bigger or smaller

Expansion and contraction (copy) When the metal was heated, we gave the particles more energy. This caused them to vibrate faster, move further apart and therefore EXPAND. The particles CONTRACT when cooled back down because they have lost energy and aren’t vibrating as fast. The particles themselves do not change size, it is the space between them that gets bigger or smaller.

For homework.. Think and write a few sentences on a situation where this (heating causing expansion) would be a problem.