Particles and Matter

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infoWhy this? The particle model explains why solids, liquids, and gases have different properties and how materials respond to heating, cooling, and changes in pressure. Using this model enables us to explain and predict changes of state, diffusion, gas pressure, and the suitability of materials for particular purposes.

scheduleWhy now? Building on primary study of materials and reversible changes, this unit moves from observable properties to explanations based on particles and energy. It provides essential foundations for separation methods later in Year 7 and for subsequent study of chemical reactions, atomic structure, and matter.

Materials are made up of particles.
The particle model of matter describes materials as being composed of tiny particles arranged and moving in specific ways.
Solids, liquids, and gases have distinct properties due to differences in particle arrangement and movement.
Particles in a solid vibrate about fixed positions in a regular arrangement; particles in a liquid are close together, irregularly arranged, and move past one another; particles in a gas are widely spaced and move rapidly and randomly in all directions.
The properties of materials, such as shape, volume, compressibility, and flow, are explained by the particle model.
Evaporation is the process where a liquid changes into a gas at the surface below its boiling point.
Condensation is the process where a gas changes into a liquid.
Melting is the process where a solid turns into a liquid.
Freezing is the process where a liquid turns into a solid.
Sublimation is the process where a solid changes directly into a gas without becoming a liquid.
Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.
The state of a substance at a given temperature can be predicted using its melting point and boiling point.
Changes of state involve changes in the energy of the particles.
Gas pressure is caused by particles colliding with the walls of their container.
Increasing the number of gas particles increases the pressure in a container when the temperature and volume remain constant.
Heating a gas increases the speed of its particles, which increases pressure if the volume and number of particles are fixed.
Racing car tyres are heated before a race primarily to bring the rubber to its operating temperature and improve grip, although heating the gas inside the tyres can also increase its pressure.
An inflated balloon expands in a warmer room because the gas inside expands as its particles move faster, and it contracts in a cooler room as the gas contracts.

rocket_launchYou must be able to

Use models, such as Lego bricks or people, to represent the arrangement and movement of particles in solids, liquids, and gases.
Draw accurate particle diagrams for solids, liquids, and gases, showing differences in arrangement and movement.
Draw before and after particle diagrams to represent changes of state, including melting, freezing, evaporation, condensation, and sublimation.
Draw before and after particle diagrams to show the process of diffusion.
Describe and explain the properties of different materials using the particle model, such as why solids have fixed shapes and why gases can be compressed.
Suggest suitable materials for particular functions based on their properties and the particle model.
Predict the state of a substance at a given temperature using data about its melting and boiling points.
Explain changes of state in terms of energy changes in the particles, such as particles gaining energy when melting or evaporating.
Explain the link between temperature and diffusion, stating that higher temperature increases the rate of diffusion.
Use appropriate scientific keywords to describe gas pressure, such as collision, force, area, and pressure.
Explain, using the particle model, why adding more gas particles increases pressure when temperature and volume remain constant.
Explain that racing car tyres are heated primarily to improve grip by bringing the rubber to its operating temperature, and use the particle model to explain why heating the gas inside can also increase its pressure.
Explain, using the particle model, why an inflated balloon expands when moved to a warmer room and contracts when moved to a cooler room.
Carry out a practical investigation to determine the best temperature of water for making tea, considering the rate of diffusion.

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