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SavannahYear 8
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ScienceParticles and matter25 min★★ difficulty

Gas pressure and the particle model

Air feels like nothing, yet it presses on every surface with about 100,000 newtons per square metre. The particle model explains exactly why.

Part of your national curriculum
  • Chemistry: the particulate nature of matter: Understand the properties of the different states of matter in terms of the particle model, including gas pressure

Lesson overview

What you'll learn in this lesson

Understand the properties of the different states of matter in terms of the particle model, including gas pressure

Key learning points

  • • Three states, one model
  • • Where pressure comes from
  • • Everyday consequences

This lesson at a glance

  • 25 minutes
  • 16 parts to scroll through
  • 4 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

propertiesstatesmatterparticlepressure

Scroll down — the lesson carries on below

Part 1 of 16 · Discover6%
1

Watch & discover

Part 1 of 16

Watch first

Gas pressure and the particle model

An English teaching video on this topic from James and Chris Science Videos. Watch it, then scroll down for the lesson.

In a nutshell

Understand the properties of the different states of matter in terms of the particle model, including gas pressure

2

Learning cycle

Part 2 of 16

Learning cycle 1 of 2

Part 1 · Three states, one model

A short piece of teaching, then a check to make sure it has landed.

3

Explore the idea

Part 3 of 16

Learn

Three states, one model

In a solid, particles vibrate in fixed positions, so shape and volume are fixed. In a liquid, particles touch but slide past one another, so the shape changes but volume does not. In a gas, particles are far apart and move fast in all directions, so a gas fills its container.

4

Explore the idea

Part 4 of 16

Learn

Where pressure comes from

Gas pressure is the total effect of countless particle collisions with a surface. More particles in the same space means more collisions per second and higher pressure. Heating a fixed volume of gas makes particles move faster, so each collision is harder and pressure rises.

5

Quick check

Part 5 of 16

Quick check

What causes gas pressure?

6

Quick check

Part 6 of 16

Quick check

What happens to pressure when a gas is heated at fixed volume?

7

Reset break

Part 7 of 16

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
8

Learning cycle

Part 8 of 16

Learning cycle 2 of 2

Part 2 · Everyday consequences

A short piece of teaching, then a check to make sure it has landed.

9

Explore the idea

Part 9 of 16

Learn

Everyday consequences

A bicycle tyre gets harder as more air is pumped in; a sealed can bulges when heated; a plastic bottle taken up a mountain and sealed crumples on the way down as outside pressure rises again.

10

Quick check

Part 10 of 16

Quick check

Why does a gas fill its container?

11

Quick check

Part 11 of 16

Quick check

Which state has fixed volume but changing shape?

12

Explore the idea

Part 12 of 16

Worked example

Worked example: a sealed syringe

The nozzle of a syringe is blocked and the plunger is pushed halfway in. Explanation: the same number of particles now occupies a smaller volume, so collisions with the walls happen more often and pressure rises. The plunger springs back because that raised pressure pushes outwards.

13

Challenge round

Part 13 of 16

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

14

Challenge round

Part 14 of 16

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

Gas pressure is the total effect of countless ____ collisions with a surface.

More particles in the same space means more collisions per second and higher ____.

15

Mastery quiz

Part 15 of 16

Marked quiz

End of lesson quiz: Gas pressure and the particle model

4 questions, marked with the reasoning shown. No timer.

  1. 1. Which statement about particles in a gas is correct?

  2. 2. What causes gas pressure?

  3. 3. What happens to pressure when a gas is heated at fixed volume?

  4. 4. Why does a gas fill its container?

16

Lesson round-up

Part 16 of 16

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

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Part 1 of 16 · Watch & discover

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    Understand the properties of the different states of matter in terms of the particle model, including gas pressure

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