Solids, Liquids, Gases

AIM:

To introduce the concept of atoms and their behaviour / arrangements in solids, liquids, and gases, including diffusion of gas atoms.

CURRICULUM LINKS:

KS2: Sc3 Materials and their Properties, Grouping and Classifying Materials. 1(e)

TIME:

20 minutes. 5 minutes explanation, 10 minutes S,L,G exercise, 5 minutes diffusion of molecules exercise.

MATERIALS REQUIRED:

Per class:

• Masking tape
• Large floor space
• Smelly perfume
• 4/5 Coloured hats or other (to distinguish the 'smelly' atoms/molecules)

METHODS:

Solids, Liquids, & Gases

• Mark out beforehand, using the masking tape, a box on the floor large enough to fit all the children inside when standing close together. Extend this box so that the area is twice as large
• Ask the children to name some solids, liquids, and gases. Do they know the smallest thing that materials are made of? Introduce the concept of atoms/molecules
• Ask the children to stand inside the smallest box. Explain that they are all atoms in a solid, and that atoms in a solid behave as we do when we are cold and ask them to shiver. The scientific word for this is vibrate
• Discuss with them what would happen if the 'atoms' had more energy, i.e. heated up a little.
• Explain that the solid has become a liquid
• Ask them to start walking around, allowing them to naturally fill the space up to the outer box.
• Discuss what happened when they moved around more? Did they bump into each other? What has happened to the size of the area the 'atoms' fill?
• Ask them what would happen if the 'atoms' had even more energy. Let the children begin to move faster and jog around the room, filling the space, like a gas
• Discuss what is happening? Do the 'atoms' bump into each other even more? What about the area they move in?
• Do the above in reverse, cooling the 'atoms' back to a solid to reinforce the concepts illustrated.

Diffusion

• Ask the children if they recall smelling their dinner being cooked whilst in another room. Explain that the smell is made up of particles/molecules which travel through the air, a gas, and that this is easily demonstrated and is called diffusion
• Line the children up single-file in a semicircle, all facing to the centre. Ask them to stand still and put up their hand when they can smell the perfume
• Standing centrally, spray the perfume from one end of the semicircle to the other.
• Watch as a wave of hands appear
• Explain what is happening to the smelly molecules
• Illustrate this further by choosing a small group of children to be smelly molecules (wearing hats), and a couple of children to be a 'nose'. Stand the 'smell' on the opposite side of the room to the 'nose'. The rest of the children will be the gas
• Squirt the 'smelly' molecules into the gas, who should jog randomly as the gas molecules do, and ask the nose to put up their hands when the smell reaches them
• Discuss what happens to the 'smell'

THEORY:

• Everything around us is made up of tiny particles called atoms which we can not see with our eyes
• Atoms are always moving
• In solids the atoms are close together and vibrate on the spot
• In liquids the atoms have more energy and so can move about a little bit more
• In gases the atoms have even more energy and are so free to move about rapidly
• Energy is needed to change from a solid, to a liquid, and then to a gas. As the atoms move more quickly they are more likely to collide. This induces an increase in volume
• All atoms/molecules in a gas move in the same way
• When the 'smell' is released it moves around as it has a lot of energy and the smelly atoms/molecules bump into other atoms/molecules in the air, eventually spreading throughout the air, known as diffusion.
• This is why it takes time for the smell from the perfume takes time to reach our noses

WEB LINKS:

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