A complete revision and exam practice pack for SC7a Molecular Compounds, covering C1.34 and C1.39.

Topic Mastery Sheet (PDF) - a comprehensive student reference built around the most important distinction in this topic: the difference between the strong covalent bonds within molecules and the weak intermolecular forces between them. When a simple molecular substance melts or boils, it is the weak forces between molecules that are overcome - the covalent bonds within each molecule remain completely intact. This is why simple molecular substances have low melting and boiling points despite having strong internal bonds. The sheet explains why larger molecules have higher boiling points: greater surface area means stronger intermolecular forces and more energy needed for separation - illustrated with the lauric/myristic/palmitic/stearic acid melting point series from the core practical. Electrical non-conductivity is explained by the absence of free electrons and ions. The polymer section explains how thousands of ethene monomers join to form poly(ethene), a long chain of carbon atoms with much stronger total intermolecular forces than the monomer - explaining why poly(ethene) melts well above ethene. The stretch section covers van der Waals forces, dipole-dipole interactions and hydrogen bonding.

Student Exam Practice Sheet (PDF + DOCX) - six questions (10 marks) covering low boiling point reasoning, low melting point explanation with forces distinguished, why poly(ethene) doesn’t conduct, what a polymer is, the boiling point trend with chain length, and the monomer of poly(ethene).

Teacher Answer Key (PDF + DOCX) - full tick-point mark scheme with examiner notes.

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