Year 7 Particles and States of Matter Worksheet - Intermediate

Year 7 Particles and States of Matter worksheet for Year 7 (Key Stage 3 / Year 7-9 (Ages 11-14)). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 3 / Year 7-9 (Ages 11-14)•Particles and States of Matterintermediate

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Particles, States of Matter and Separating Mixtures

Year 7 Science | Ages 11–12 | Intermediate

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Instructions: Complete the six activities using the information in each question. Use scientific vocabulary and explain your reasoning where asked; show working for calculations. Write each answer in the space provided.

The Particle Model

Use the particle model to compare solids, liquids and gases. Give clear scientific reasons rather than describing only what you can see. Each response should include the relevant arrangement or movement of particles.

1. In a solid, how are the particles arranged, and how do they move? [3 marks]

2. Explain why a liquid can flow but keeps a fixed volume. [3 marks]

3. A gas spreads out to fill its container. Explain this using the spacing and movement of its particles. [3 marks]

4. A sealed syringe contains air. What happens to the gas particles when the plunger is pushed in, and why can the air be compressed? [3 marks]

Changes of State

Name each change of state and explain what happens to the particles as energy is transferred. Use the terms solid, liquid and gas accurately. Remember that sublimation happens without the substance becoming liquid first.

1. Ice changes from a solid to liquid water when heated. Name the change and describe what happens to the particles. [3 marks]

2. Water vapour changes into liquid droplets on a cool window. Name the change and state whether energy is transferred to or from the substance. [2 marks]

3. Liquid water changes into water vapour throughout the liquid at its boiling point. Name the change. [1 mark]

4. Solid iodine changes directly into purple gas when heated. Name this change of state. [1 mark]

5. Liquid water becomes ice in a freezer. Name the change and describe the energy transfer. [2 marks]

Diffusion and Density

Use the observations and measurements in the questions to explain particle movement and density. For the calculation, use density = mass ÷ volume and include the correct unit. Give a reason for each explanation.

1. A drop of food colouring spreads through still water. Name the process and explain how the particles cause it. [3 marks]

2. The colouring spreads faster in warm water than in cold water. Explain why, using particle movement. [2 marks]

3. A metal block has a mass of 54 g and a volume of 20 cm³. Calculate its density in g/cm³. [2 marks]

4. A warm gas is less dense than the same gas when cool, at the same pressure. Explain this using particle spacing. [2 marks]

Pure Substances and Mixtures

Classify each sample as a pure substance or a mixture. A pure substance contains only one substance; a mixture contains two or more substances together. Use the examples to support your choices.

1. Distilled water contains only water particles. Is it a pure substance or a mixture? [1 mark]

2. Air contains several gases, including nitrogen and oxygen. Is it a pure substance or a mixture? [1 mark]

3. A beaker contains salt dissolved in water. Is the sample a pure substance or a mixture? [1 mark]

4. A sealed sample contains only oxygen particles. Is it a pure substance or a mixture? [1 mark]

Choosing a Separation Method

Choose the most suitable method for each mixture from this word bank: filtration, evaporation, simple distillation, chromatography. Use each method once. Think about whether the substances are dissolved, insoluble, or have different boiling points.

Word bank: filtration, evaporation, simple distillation, chromatography

1. Separate insoluble sand from water. [1 mark]

2. Recover dissolved salt from salt solution when the water does not need to be collected. [1 mark]

3. Obtain pure water from a solution of copper sulphate by boiling the water and collecting its vapour after it condenses. [1 mark]

4. Separate the different dyes in a water-soluble ink. [1 mark]

Separation Data: Paper Chromatography

Read the results table. Each value is the distance a dye travelled from the pencil baseline. Answer the questions by comparing the recorded distances. In this experiment, the solvent front travelled 8 cm.

Dye	Distance travelled (cm)	Colour
Blue	6	Blue
Red	4	Red
Yellow	2	Yellow
Green	6	Green

1. Which dye travelled the furthest? [1 mark]

2. Which dye travelled the shortest distance? [1 mark]

3. How far did the blue dye travel compared with the yellow dye? [1 mark]

4. Which two dyes travelled the same distance? [1 mark]

Answer Key

Activity 1: 1. Particles are closely packed in a regular arrangement and vibrate about fixed positions. 2. Particles are close together but can move past one another; their close spacing keeps the volume fixed. 3. Gas particles are far apart and move rapidly in random directions, spreading to fill the available space. 4. The particles are forced closer together; there is space between gas particles, so the gas can be compressed.

Activity 2: 1. Melting; particles gain energy and vibrate/move more until they can move past one another. 2. Condensing; energy is transferred from the water vapour. 3. Boiling. 4. Sublimation. 5. Freezing; energy is transferred from the water to the surroundings.

Activity 3: 1. Diffusion; particles move randomly and spread from a region of higher concentration into the water. 2. In warm water, particles have more energy and move faster, so diffusion happens more quickly. 3. 54 ÷ 20 = 2.7 g/cm³. 4. The warm gas particles move faster and are more spread out, so there is less mass in the same volume.

Activity 4: 1. Pure substance. 2. Mixture. 3. Mixture. 4. Pure substance.

Activity 5: 1. Filtration. 2. Evaporation. 3. Simple distillation. 4. Chromatography.

Activity 6: 1. Blue and green (6 cm). 2. Yellow (2 cm). 3. Blue travelled 4 cm further than yellow. 4. Blue and green.