This memory aid covers Memory Aids within Simple Molecules for GCSE Chemistry. Revise Simple Molecules in Bonding & Structure for GCSE Chemistry with 20 exam-style questions and 21 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 8 of 11 in this topic. Use it for quick recall, then test yourself straight afterwards so the memory aid becomes usable in an answer.
🧠 Memory Aids
Bonds DON'T break, forces DO: When a simple molecular substance melts, the intermolecular FORCES between molecules break. The covalent BONDS inside molecules do NOT break. Remember this by contrast: salt melting breaks the ionic lattice; ice melting breaks the intermolecular forces between H₂O molecules.
Size → Strength → State:
- Larger molecule → more intermolecular forces → higher melting point
- O₂ (tiny) = gas at room temp; wax (large) = solid at room temp
State at room temperature memory trick:
- O₂, N₂, CO₂, CH₄, NH₃, HCl → all gases (tiny molecules, very weak forces)
- H₂O, Br₂, Hg → liquids (slightly stronger forces)
- I₂, wax → solids (larger molecules, stronger forces)
Practice questions for Simple Molecules
Which type of force holds simple molecules together as a substance?
Explain why chlorine (Cl2) has a low boiling point.