CCEA A-Level Chemistry AS 1 Basic Concepts: a complete overview of atomic structure, the mole, bonding, energetics, kinetics and equilibrium

What this module demands

AS 1 Basic Concepts in Physical and Inorganic Chemistry is the foundation of the whole CCEA qualification. It blends quantitative skills (the mole, energetics and equilibrium calculations) with the core models of bonding, redox and reaction rate. The examiners reward fluent calculation, precise definitions and the ability to apply the bonding and equilibrium models to unfamiliar examples.

This guide walks through the eight dot points of the module, then sets out the exam patterns CCEA repeats. Each topic has a matching dot-point page with practice questions; this overview ties them together.

Atomic structure and amount of substance

Atomic structure covers sub-atomic particles, isotopes, the time-of-flight mass spectrometer, electron configuration in s, p and d sub-shells, and ionisation energy evidence for shells. Amount of substance is the calculation core: the mole and the Avogadro constant, molar mass, empirical and molecular formulae, the ideal gas equation $pV = nRT$, solution concentrations, titrations, percentage yield and atom economy. Master the unit conversions, especially $\text{cm}^3$ to $\text{dm}^3$.

Bonding, structure and intermolecular forces

Bonding and structure covers ionic, covalent and metallic bonding, the four crystal structures, and molecular shapes predicted by electron-pair repulsion. Intermolecular forces are the attractions between molecules, ranked from van der Waals (London) forces through permanent dipole-dipole forces to hydrogen bonding, and they explain trends in boiling point, solubility and the anomalous behaviour of water and ice.

Redox and energetics

Redox chemistry tracks electron transfer using oxidation numbers, identifies oxidising and reducing agents, and builds balanced equations from half-equations. Energetics measures enthalpy changes by calorimetry ($q = mc\Delta T$), defines the standard enthalpies of combustion, formation and neutralisation, applies Hess's law through enthalpy cycles, and estimates $\Delta H$ from mean bond enthalpies.

Kinetics and equilibrium

Kinetics uses collision theory and the Maxwell-Boltzmann distribution to explain how concentration, pressure, surface area, temperature and catalysts change reaction rate. Equilibrium describes dynamic equilibrium in reversible reactions, applies Le Chatelier's principle, introduces the equilibrium constant $K_c$, and explains the compromise conditions of industrial processes such as the Haber process.

How this module is examined

A typical CCEA profile for AS 1:

• Calculations. Mole, titration, ideal gas, yield, atom economy, calorimetry, Hess's law and bond enthalpy questions, with marks for working and units.
• Definitions and rules. Isotopes, electronegativity, enthalpy terms, oxidation number rules and equilibrium definitions, tested by name.
• Models and shapes. Predicting molecular shapes and bond angles, ranking intermolecular forces, and sketching the Maxwell-Boltzmann distribution.
• Application. Applying Le Chatelier's principle to the Haber process and explaining the effect of conditions on rate and yield.

Check your knowledge

A mix of recall and calculation questions covering the module. Attempt them under timed conditions, then check against the solutions.

1. Define the term isotopes. (2 marks)
2. State the relationship used to find moles from mass, and from concentration and volume. (2 marks)
3. Predict the shape and bond angle of a molecule of ammonia. (2 marks)
4. Name the strongest intermolecular force and state the condition for it. (2 marks)
5. State the oxidation number of sulfur in the sulfate ion. (1 mark)
6. State Hess's law. (1 mark)
7. State the two conditions for a successful collision. (2 marks)
8. State the effect of a catalyst on the position of equilibrium. (1 mark)