Particles and States of Matter Worksheet - KS3 - Beginner

Particles and States of Matter worksheet for KS3 (Key Stage 3 / Year 7-9 (Ages 11-14)). Beginner 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 Matterbeginner

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Particles and States of Matter

Key Stage 3 • Ages 11–14 • Beginner

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Instructions: Work through the activities in order. Use the particle model to explain what happens to particles, not just what happens to the material. Write your answers in the boxes; use the word bank where provided.

The particle model

Use the word bank to complete each sentence. Choose each word that best fits the sentence. Remember: particles in a solid are close together and vibrate about fixed positions.

Word bank: fixed positions, slide past, far apart, vibrate, random motion

1. In a solid, particles are close together and ________.

2. In a liquid, particles are close together but can ________ one another.

3. In a gas, particles are usually ________ compared with particles in a solid or liquid.

4. Particles in every state of matter are always moving; solid particles ________ about their positions.

5. Gas particles move quickly in ________ directions.

Compare the three states

For each state, describe how its particles are arranged and how they move. Use the words close together, fixed positions, slide past and random motion where they help. Keep each answer to a clear sentence.

1. How are particles arranged and how do they move in a solid?

2. How are particles arranged and how do they move in a liquid?

3. How are particles arranged and how do they move in a gas?

4. Which state has particles that are furthest apart?

Changes of state

Name the change of state in each example. Use the word bank, then think about whether the substance gains or loses thermal energy. Each change has a specific scientific name.

Word bank: melting, freezing, boiling, condensing, gains, loses

1. Solid ice changes into liquid water. The change is ________.

2. Liquid water changes into solid ice. The change is ________.

3. Liquid water changes into water vapour throughout the liquid. The change is ________.

4. Water vapour changes into liquid water. The change is ________.

5. During melting, a substance ________ thermal energy.

6. During freezing, a substance ________ thermal energy.

Diffusion in everyday life

Diffusion is the spreading of particles from a region where they are more concentrated to a region where they are less concentrated. Use this idea to answer each question. Explain your reasoning in a sentence where asked.

1. A drop of food colouring spreads through still water. What process causes it to spread?

2. A room fills with the smell of perfume after it is sprayed near the door. In which direction do the perfume particles spread: from higher to lower concentration, or lower to higher concentration?

3. Why does diffusion usually happen faster in a warm room than in a cold room?

4. Name the state of matter in which diffusion is generally fastest: solid, liquid or gas.

Gas pressure and particle collisions

Gas particles move randomly and collide with the walls of their container. These collisions exert a force; the force over an area produces pressure. Use this model to explain your answers.

1. What causes a gas to exert pressure on the walls of its container?

2. A sealed syringe contains air. The plunger is pushed in, reducing the volume. What happens to the frequency of particle collisions with the syringe walls?

3. When the air in a sealed container is heated, its particles move faster. What happens to the pressure if the container’s volume stays the same?

4. A container has no gas particles inside it. What pressure would the gas particles exert on its walls?

Answer Key

Activity 1: fixed positions ; slide past ; far apart ; vibrate ; random motion

Activity 2: 1. Particles are close together and vibrate about fixed positions. ; 2. Particles are close together and can move or slide past one another. ; 3. Particles are far apart and move quickly in random directions. ; 4. Gas

Activity 3: melting ; freezing ; boiling ; condensing ; gains ; loses

Activity 4: diffusion ; from higher to lower concentration ; particles have more kinetic energy and move faster when warm ; gas

Activity 5: 1. Moving gas particles collide with the container walls and exert force on them. ; 2. Collisions with the walls happen more frequently. ; 3. Pressure increases. ; 4. Zero pressure from gas particles