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Changes of state and the particle model
This topic links measurable density to the arrangement and motion of particles in solids, liquids and gases, then uses that model to describe changes of state.
30
Objectives
150
Flashcards
150
Questions
90 min
Study time
AQAGCSEPhysicsParticle model of matter
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Syllabus checklist
What you need to know
30 objective pages available
Density of materials16 objectives
- Define density as mass per unit volume.
- Recall and apply the equation density = mass divided by volume.
- Identify density in kilograms per metre cubed or grams per centimetre cubed, mass in kilograms or grams and volume in metres cubed or centimetres cubed.
- Calculate density when mass and volume are known.
- Calculate mass when density and volume are known.
- Calculate volume when mass and density are known.
- Rearrange the density equation to solve for mass, volume or density.
- Required practical activity 5: use appropriate apparatus to make and record measurements needed to determine densities of regular solid objects.
- Required practical activity 5: use appropriate apparatus to determine densities of irregular solid objects.
- Required practical activity 5: use appropriate apparatus to determine densities of liquids.
- Describe how to determine the volume of a regular solid using length measurements.
- Describe how to determine the volume of an irregular solid using displacement of water.
- Describe how to determine the density of a liquid using a balance and measuring cylinder.
- Apply AT 1 and AT 3 skills when measuring mass and volume.
- Apply MS 1c and MS 3c skills when using standard form, significant figures and rearranging the density equation.
- Compare densities of materials using calculated or measured values.
Changes of state14 objectives
- Describe solids, liquids and gases in terms of particle arrangement and movement.
- Explain melting using increased particle energy and changed particle arrangement.
- Explain freezing using decreased particle energy and changed particle arrangement.
- Explain boiling using particles gaining enough energy to separate throughout a liquid.
- Explain evaporation as particles escaping from the surface of a liquid.
- Explain condensing using decreased particle energy and closer particle arrangement.
- Explain sublimation as a change directly between solid and gas.
- Distinguish boiling from evaporation using where and how the change occurs.
- State that changes of state are physical changes.
- Explain that mass is conserved when a substance changes state.
- Explain that the material recovers its original properties if a change of state is reversed.
- Use the particle model to explain why solids have fixed shapes and liquids and gases flow.
- Use the particle model to explain why gases are less dense than solids or liquids.
- Describe limitations of simple particle model diagrams for representing real particles, forces and motion.
Key terms
DensityMassVolumeRearranging the Density EquationRegular SolidIrregular SolidLiquiddisplacementirregular solidMeasuring CylinderMeasured ValuesParticle Arrangement
Exam tips
- Understand Density: Remember that density is defined as mass per unit volume. Use the formula density = mass/volume to solve problems.
- Mastering Density Calculations: Remember to practice rearranging the density equation to solve for mass, volume, or density in various scenarios. Link your answer to Density of materials in Changes of state and the particle model.
Common mistakes
- Confusing Density with Weight: Remind students that density is defined as mass per unit volume, and that two objects can have the same weight but different densities if their volumes differ.
- Common Mistake in Density Calculation: Always ensure you are using the correct values for mass (in kg or g) and volume (in m³ or cm³) before substituting them into the density equation.
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