Its all about the particles- change of state LO: To explain changes of state in terms of particles TASK In this picture, Discuss with your partner, how do the people act like particles in solids, liquids and gases. How is this analogy incorrect?

Soldiers standing in rank

Dancers on a crowded dance floor

Players running around on a football pitch

Particles in a solid Particles do not change position but vibrate in same place

Particles in a liquid Particles can move past each other

Particles in a Gas Particles move very quickly and there is empty space between the particles

Ball and ring demo In your book, explain what happens to the arrangement of particles in a solid when it is heated Start the explanation with this sentence When a solid is heated, the particles……..

Particulate Model of Matter Expansion Contraction When a substance is heated, the particles move faster and further apart. Therefore it expands. On cooling, the substance contracts as the particles move slower and come closer together. The particles DO NOT get bigger, the spaces between particles get bigger S1 Science 2009: PMM Lesson 1

Particulate Model of Matter The particles are close together and cannot move about. The particles far apart and move very quickly and randomly. The particles move faster and further apart. S1 Science 2009: PMM Lesson 1

Heating ice- draw the heating curve of ice on mini white board Temp/OC 150 100 50 -50 This flat line shows where energy is being used to push the particles further apart for evaporation Use IWb This flat line shows where energy is being used to break bonds – this has to be done during melting Time/s

Questions Questions When will the temperature be hottest, in summer or winter? Why are telephone lines tight in the winter but slack in the summer? Telephone lines in summer - What would happen if the wires were put up so they were tight in the summer?

How does as ice cube melt assessment As an ice cube is heated, the particles……….. As water is heated, the particles

Homework Answer Expansion worksheet questions in your book Wednesday - Some solids expand more than others - When you join 2 strips of metal together it is called a bimetallic strip

Expansion This picture shows a bimetallic strip. It is a strip of two different metals joined together. It bends when it gets hot because one metal expands more than the other. It straightens out again when it gets cold.    1 Does the picture show the strip when it is hot or cold?  2 What will happen if the temperature goes down? The strip is part of a switch. When the strip touches the contact, electricity can flow and switch the central heating on. This is called a thermostat.  3 How does the thermostat help to keep a house at a constant temperature? 4 Draw a switch (similar to the one above) that would switch on air conditioning if the temperature got too hot.

True or False Particles get bigger when a solid is heated Energy is needed for a solid to melt and turn into a liquid

Heating jelly Draw what the particles look like before and after heating What is happening to the substance during heating?

Diffusion demos: Purple crystals in room temperature water Purple crystals being heated in bunsen Purple crystals in beaker being stirred

Diffusion 3 Here is a simple experiment in which two gases diffuse towards each other in a glass tube. When they meet they will react to form a cloud of white smoke. Cotton wool soaked in ammonia solution Cotton wool soaked in hydrochloric acid (concentrated) Where do you think the white smoke will form? Did it form where you thought it would? Why did it form here? Use particles in your explanation

What do you think will happen as the size and number of particles is increased?

Plenary