In this chapter we are going to review what we know about solids, liquids and gases. This diagram compares the particles in a gas, a liquid and a solid. The particles are closely packed and cannot move from their positions.Д®ach state of matter behaves differently and the particles in each state behave differently.The particles are close together but they can move around.Liquids can flow to fill the container.The particles are far apart and can move freely.Gases spread out and will escape if they are not in a closed container.Some of the properties that learners should already be familiar with are listed in the following table: Out of the class, three groups could be chosen randomly, and each group could say what they know about one of the states. Get learners to discuss this briefly in small groups and draw a table on the board to summarise learners' ideas. What happens to pressure when we change its volume and temperature?Д¬an you remember learning that matter can exist in three different states? What are the three states called?.Is the pressure a gas exerts related to the number of gas particles? If so, how?.How can the particle model of matter help us to understand expansion and contraction?.Why does oil float on water? Is this related to density?.Which aspects of the particles in a given material influence the density of that material?.How do the densities of solids, liquids and gases compare?.How are density, mass and volume related to each other?.How does the particle model of matter help us to understand changes of state in materials, such as melting, evaporation, condensation and freezing?.How can materials be made to change their state?.How does the particle model of matter help us understand the process of diffusion?.How does the particle model of matter describe solids, liquids and gases?.Hypothesising, identifying variables, planning investigation, doing investigation, observing, recording information, interpreting informationДemonstrating densities, comparing, observing, drawing, comparingДў.7 Expansion and contraction of materials (2 hours)Дrawing graphs, interpreting information, predicting, demonstratingДЇollowing instructions, observing, interpreting information Investigation: Comparing the densities of sand, flour, water and air Predicting, hypothesising, planning investigation, drawing and labelling, observing, recording, analysing informationДoing investigation, observing, comparing, communicating and group discussionДў.5 Density and states of matter (1 hour)ДЄctivity: Which has the highest density: a solid, a liquid or a gas?Дў.6 Density of different materials (3 hours) Investigation: What happens when we heat and then cool candle wax? Hypothesising, observing, identifying variables, recording information, comparing, interpreting informationД¬rossword puzzle, reading and writing, sorting and classifying Investigation: Comparing the diffusion of particles in a gas and in a liquid 10-12.Дў.1: What is the particle model of matter? (1 hour)ДЄccessing and recalling information, revisingДЄctivity: Comparing solids, liquids and gasesДЄccessing and recalling information, comparing The particle model of matter will be a strong theme throughout the rest of the Physical Sciences curriculum, especially if learners continue through to Gr. Important links are made to new concepts such as diffusion, changes of state, density, expansion, contraction and gas pressure. In this chapter these ideas are further expanded, using the particle model of matter. The behaviour of particles in each of the three different states of matter was used to explain the macroscopic properties of each state. This was the first introduction to the concept of matter particles. These were grouped together and the generic term 'particle' was used to refer to these fundamental building blocks of matter. 6, no distinction was made between atoms and molecules. This chapter builds on the introduction to the arrangement of particles in materials that was covered in the chapter 'Solids, Liquids and Gases' of the Gr.

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