The AP Chemistry exam is built around nine key units that cover the foundations of chemical science. Understanding what each unit includes and how much it’s worth can transform your study plan from guesswork into a strategic, high-scoring approach.
This guide covers all 9 AP Chem units, their exam weight, and targeted tips for each.
AP Chemistry Units & Weighting
The College Board organizes AP Chemistry into the following units:
Unit 1 — Atomic Structure and Properties
Weight: 7–9% of the exam
Key Topics:
- Structure of the atom
- Electron configurations and periodic trends
- Photoelectron spectroscopy (PES)
Tip: Memorize periodic trend patterns — they are often tested in MCQs.
Unit 2 — Molecular and Ionic Compound Structure and Properties
Weight: 7–9%
Key Topics:
- Bond types (ionic, covalent, metallic)
- Lewis structures and resonance
- VSEPR theory and molecular geometry
Tip: Practice drawing Lewis structures until it’s second nature.
Unit 3 — Intermolecular Forces and Properties
Weight: 18–22%
Key Topics:
- Types of intermolecular forces (IMFs)
- Properties of liquids, solids, and gases
- Solutions and solubility
Tip: IMFs are frequently tested in both MCQ and FRQs — know your hydrogen bonds from your London dispersion forces.
Unit 4 — Chemical Reactions
Weight: 7–9%
Key Topics:
- Balancing equations
- Types of reactions (synthesis, decomposition, etc.)
- Net ionic equations
Tip: Always include state symbols in net ionic equations for full credit.
Unit 5 — Kinetics
Weight: 7–9%
Key Topics:
- Reaction rates and rate laws
- Determining order of reactions
- Collision theory
Tip: Be comfortable with rate law graphs and integrated rate equations.
Unit 6 — Thermodynamics
Weight: 7–9%
Key Topics:
- Endothermic vs exothermic
- Enthalpy, entropy, and Gibbs free energy
- Calorimetry
Tip: Remember ΔG=ΔH−TΔS\Delta G = \Delta H - T\Delta S — it appears often in FRQs.
Unit 7 — Equilibrium
Weight: 7–9%
Key Topics:
- Le Châtelier’s principle
- Calculating KeqK_{eq}
- Reaction quotient QQ
Tip: Know when to use ICE tables — they are critical for calculation questions.
Unit 8 — Acids and Bases
Weight: 11–15%
Key Topics:
- pH, pOH, and the pKw relationship
- Strong vs weak acids/bases
- Titrations and buffer systems
Tip: Memorize the strong acids and bases list to save time on the exam.
Unit 9 — Applications of Thermodynamics
Weight: 7–9%
Key Topics:
- Electrochemistry and redox reactions
- Cell potential calculations
- Relationship between ΔG\Delta G and EcellE_{cell}
Tip: Be able to calculate cell potentials from half-reactions.
Why Unit Weighting Matters
Knowing that IMFs (Unit 3) and Acids & Bases (Unit 8) are heavier on the exam lets you prioritize your study time. A strategic plan focuses more on high-weight topics while still reviewing smaller units.
How RevisionDojo Helps You Master Every AP Chem Unit
With RevisionDojo, you can:
- Access Unit-Specific Practice Sets aligned with College Board guidelines
- See Past Exam Questions categorized by unit
- Get Detailed Solutions to learn from your mistakes
- Track Your Weakest Units with analytics and targeted quizzes
And when your score is in:
- University Match Quiz — Find out where your AP Chem score earns you credit.
- Universities Directory — Compare AP credit policies for chemistry courses worldwide.
FAQ – AP Chem Units
1. How many units are in AP Chemistry?
Nine units, ranging from atomic structure to electrochemistry.
2. Which AP Chem unit is hardest?
Many students struggle with Unit 8 (Acids & Bases) due to multi-step calculations.
3. Which units have the most exam weight?
Unit 3 (IMFs) and Unit 8 (Acids & Bases) carry the highest percentage.
4. Should I memorize all formulas?
Some are provided, but many essential equations are not — yes, memorize them.
5. How should I study by unit?
Start with the most heavily weighted units, then review smaller ones for balance.
6. Are FRQs divided by unit?
Not exactly — many FRQs integrate concepts from multiple units.
Ace Every AP Chem Unit with RevisionDojo
Your AP Chemistry prep shouldn’t be random — it should be data-driven and strategic.
🎯 Take the University Match Quiz to find universities that give you AP Chem credit.
🌍 Explore the Universities Directory to plan your academic future.
