Questions candidates found difficult on the H1 Chemistry 8873 (Nov 2023) papers — orbitals, bonding & shapes, periodicity, redox, intermolecular forces, organic formulae and kinetics.
Atomic structure — filling p orbitals singly first (Hund’s rule)
Paper 1 Q8 — Al₂Cl₆ → AlCl₃: shape and bond angleBonding & shapes — dimer to monomer changes geometry and bond angle
Paper 1 Q10 — Volatility down Group 17Intermolecular forces — volatility depends on id–id forces, not covalent bond strength
Paper 1 Q11 — Period 3 oxides reacting with waterPeriodicity — solubility and acid/base behaviour of Na–S oxides in water
Paper 1 Q15 — Which compound contains H⁻?Redox — reduction is gain of electrons / decrease in oxidation number; the hydride ion
Paper 1 Q25 — Forces between two different polymersIntermolecular forces — no H-bonding without N–H/O–H; saturated chains cannot form new covalent bonds
Paper 1 Q28 — Molecular formula from a skeletal structureOrganic — reading skeletal formulae; counting implicit hydrogens
Paper 1 Q30 — Oxidising four primary alcohol groupsOrganic — full oxidation of primary alcohols to carboxylic acids; atom bookkeeping
Kinetics — shape of the Maxwell–Boltzmann distribution and effect of temperature/catalyst
Paper 2 Q5(b) — Ionisation energy across a periodPeriodicity — successive/first ionisation energies; the Al dip and the big jump to a new shell
Paper 2 Q7(b) — Reaction order from half-livesKinetics — constant half-life means first order; reading order from a concentration–time graph
Original reconstructions inspired by the SEAB/Cambridge Examiner Report. Not actual examination questions.
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