Chemistry · Bonding, Structure and Properties of Matter
States of Matter and State Symbols
Spec 5.2.2.1–5.2.2.2📗 Foundation
Theory · read, then commit
All matter exists in one of three states — solid, liquid or gas. The difference is how the particles are arranged and how freely they move.
🧊Solid
ArrangementRegular, closely packed
MovementVibrate about fixed positions
Shape & volumeFixed shape, fixed volume
Compressible?No
💧Liquid
ArrangementClose but random
MovementFlow past each other
Shape & volumeTakes container shape, fixed volume
Compressible?No
💨Gas
ArrangementFar apart, spread out
MovementFast, random, all directions
Shape & volumeFills any container
Compressible?Yes
How freely the particles move drives everything else — shape, volume and whether it can be compressed.
Checkpoint · quick check
Describe the arrangement and movement of the particles in a solid.
🫠Melting / Freezing
Solid ⇌ liquid. Melting adds energy; freezing removes it.
♨️Boiling / Condensing
Liquid ⇌ gas. Boiling adds energy; condensing removes it.
❄️Subliming
Some solids go straight to gas (iodine, dry ice). All these are physical changes.
Checkpoint · quick check
Name the change of state that occurs when a liquid turns into a gas.
🔤State symbols in equations
(s) solid · (l) liquid · (g) gas · (aq) dissolved in water.
2H₂(g) + O₂(g) → 2H₂O(l)
NaCl(s) → Na⁺(aq) + Cl⁻(aq)
Checkpoint · quick check
In the equation NaCl(s) → Na⁺(?) + Cl⁻(?), state the symbol that shows the ions are dissolved in water.
Retrieval · Match the State Change to its Name
Test yourself · 9 questions, exam order
⭐Examiner Tip
Melting and boiling are physical changes — the particles rearrange but the substance is unchanged (ice, water and steam are all H₂O), so don't call them chemical changes. And use the state symbol (aq) only for something dissolved in water, not for any liquid.
0 of 9 answered
Warm-up · 1 question
Ice melts to form water. State whether this is a physical or a chemical change, and explain your answer.
Exam standard · 4 questions
Explain, in terms of particles, why a gas can be compressed but a solid cannot.
Name the three states of matter.
State what happens to the particles of a solid when it melts.
Name the change of state from a gas to a liquid.
Stretch · 4 questions
State the state symbol used for a pure liquid.
Identify the state of matter in which the particles are far apart and move quickly in all directions.
Identify a pair of properties that describe a gas.
Identify the correct set of state symbols for solid, liquid, gas and dissolved-in-water.
Key note · cover it, say it, check it
Revision card · 5 stepsStates of Matter and State Symbols