Students ideas about states of matter and the particulate nature of matter are well documented and can be read about in Chapter 1 and 2 of Beyond Appearances: Student misconceptions about basic chemical ideas.

The research found many misconceptions which are summarised in the image below.

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These finding clearly show that students find it difficult to make the link between macroscopic and microscopic scales and this of course has implications for teaching and the resources that are used with and by the students.The next image shows a range of diagrams, that can be found on many websites and in some books, showing how the particals of a substance are arranged in the solid, liquid and gaseous state.

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• In turn carefully study each diagram and note down your thoughts.
• How do these diagram help or hinder students understanding of the particle model of matter?
• How do the partical diagrams given here compare to the diagrams you use in school?

Some of the particle diagrams shown in the image seem to imply that there are large gaps between the particles in a liquid. How could you help students to understand that large gaps do not exist between the particles in a liquid?

By showing that you can not compress a liquid. Fill a sealed syringe with water and then try to compress it by pushing in the plunger. The plunger will not move because the particles are already touching each other. You could then repeat the process using a gas and show that gases can be compressed.

Some of the particle diagrams shown in the image seem to imply that the particles in a solid, liquid and gas are different because some particles have 'tails' or 'arrows' coming out of them whilst other don't. How can you help your students to realise that the actual particles of a substance do not change form when they change state?

The use of animations is good for getting over this point because they show how the movement of particles changes as the state changes whilst the particles stay the same.

Role play can also be helpful, if students take on the role of the particle. Start by asking the class to line up in a regular pattern of say 6 rows of 5 students. The students should stand very close together, linking arms, and swaying slowly to represent as the particles in the solid state. In the liquid state, the students should remain close together but they can swap places or move past each other as long as they stay in close proximity. The regular pattern seen in the solid state is now more disordered and there is more movement. Finally, when modelling the particles in the gaseous state the students are free to run around within specified boundaries. During the role play, the actual students representing the particles have not changed implying that the particles do not change.