Ever wondered how A Level Chemistry exams are marked?

Examiners use a system of Assessment Objectives (AOs) to grade your work. These ensure that every student is assessed fairly across knowledge, application and analysis.

The three Assessment Objectives

All A Level Chemistry questions are mapped to one or more of these objectives:

• AO1: Knowledge & Understanding — recalling facts, definitions, equations, and standard procedures.
• AO2: Application — applying knowledge to unfamiliar situations, calculations, experiments and problem solving.
• AO3: Analysis & Evaluation — interpreting data, drawing conclusions, evaluating methods and suggesting improvements.

Weighting of AOs in Chemistry

In AQA A Level Chemistry (7405), the weighting across all papers is:

• AO1: ~35%
• AO2: ~40%
• AO3: ~25%

This ensures you’re tested on recall, problem-solving and scientific skills, not just memory.

How this looks in the exam

Here’s how the AOs typically appear in practice:

• AO1: “Define the term enthalpy change of combustion.”
• AO2: “Calculate the empirical formula given mass data.”
• AO3: “Evaluate a student’s titration method and suggest improvements.”

Most questions combine more than one AO, especially in structured problem-solving and data analysis.

Why it matters

Understanding AOs helps you tailor your revision:

• AO1: Use flashcards, definitions, and quick-fire recall.
• AO2: Practise past-paper problems and apply theory to new situations.
• AO3: Work on analysing data, writing evaluations and improving experimental design.

See AQA sample assessment resources.

Frequently Asked Questions

Which AO is the most important?

AO2 has the highest weighting, but all three are essential for exam success.

Do multiple-choice questions use all AOs?

Mostly AO1 and AO2, though some may require AO3 analysis of data or methods.

Are AOs the same across exam boards?

Yes. AQA, Edexcel and OCR all follow Ofqual rules, though the balance of AO weightings may differ slightly.

Ready to plan your exam strategy?