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1.2Chapter 1: The Particle Model and States of Matter

The states of matter — Alhussan Chemistry - Stage 7 Revision Notes & Topical Questions

5 min read 8 parts Lesson 2 of 8 2 quizzes

📚 Alhussan Chemistry - Stage 7 Hub / Topical Revision
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Lesson summary

1.2 The states of matter — Properties of Solids, Liquids and Gases — Alhussan International Academy — Chemistry (Stages 7–9) notes: Compare solids, liquids and gases in terms of particle arrangement, movement, attraction and physical properties.States — most substances can exist …

  • Same particles
  • What differs
  • Gas pressure
  • Hydraulic brakes
  • Physical property
  • States — most substances can exist as a solid, a liquid or a gas.The state depends on temperature and pressure

Part 1 of 6Three states of matter

Three states of matter
States
  • States most substances can exist as a solid, a liquid or a gas.
  • The state depends on temperature and pressure.
Physical properties
Physical properties properties you can observe or measure without changing the material.
  • Examples are whether a substance flows, whether it can be compressed and whether its shape can change.
Same particles
  • Same particles the particles are the same in all three states, so a particle in ice is the same as one in liquid water and in steam.
What differs
  • What differs the arrangement, movement, separation and attraction of the particles.

Part 2 of 6Solids

Solids
Particles
  • Particles they touch each other and are in fixed positions in a regular pattern, held together strongly.
  • They can only vibrate on the spot.
Properties
  • Properties a solid has a fixed shape and fixed volume, cannot flow and cannot easily be compressed.
  • Its shape stays the same unless a force is applied.
  • Density is high because the particles are so close.

Part 3 of 6Liquids

Liquids
Particles
  • Particles they touch each other and are held together strongly, but are not in a pattern and move around randomly, sliding over each other.
Properties
  • Properties a liquid has a fixed volume but no fixed shape, flows and takes the shape of the bottom of its container.
  • It can be compressed only a tiny bit.
  • Its density is generally lower than the solid, but ice is less dense than liquid water.

Part 4 of 6Gases

Gases
Particles
  • Particles they are far apart, not in a pattern, move very fast in all directions and are held together very weakly.
Properties
  • Properties a gas has no fixed shape or volume and fills the whole container.
  • It flows and can be compressed a lot because of the large spaces, and its density is very low.
Gas pressure
  • Gas pressure it is caused by gas particles colliding with the walls of the container.
  • Heating a gas makes the particles faster, so they hit the walls harder and more often and the pressure rises.

Part 5 of 6Comparing the three states

PropertySolidLiquidGas
ArrangementRegular pattern, touchingRandom, touchingRandom, far apart
MovementVibrate on the spotSlide over each otherMove fast in all directions
AttractionStrongStrongVery weak
ShapeFixedShape of bottom of containerFills container
VolumeFixedFixedNot fixed
FlowsNoYesYes
CompressibleNoOnly a tiny bitYes, a lot
DensityHighMediumLow

Part 6 of 6Applying the model

Syringe
  • Syringe gas can be squashed in a syringe because its particles have large spaces between them, but liquid particles are already touching.
Hydraulic brakes
  • Hydraulic brakes they use liquids because liquids transmit pressure without being compressed.
Powders
  • Powders flour can be poured like a liquid, but each grain is a tiny solid, so powders are still solids.

Key terms

TermMeaning
SolidA state with a fixed shape and volume, particles vibrating in a regular pattern.
LiquidA state with a fixed volume that flows, particles sliding past each other.
GasA state that fills its container, particles far apart and moving fast.
Physical propertyA property observed or measured without changing the material.
CompressTo squash into a smaller volume.
Gas pressureThe force from gas particles colliding with container walls.

Avoid these mistakes

1
Drawing solid particles as separated far apart.
2
Saying liquids cannot flow because particles are fixed.
3
Thinking gas particles are lighter or smaller than in the liquid — they are the same particles.
4
Writing that particles expand when heated — they move faster and spread out.

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