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AP Chemistry

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AP Chemistry runs from atomic structure and periodicity through bonding and molecular geometry, intermolecular forces, stoichiometry and solutions, kinetics, thermodynamics, equilibrium, acids and bases, and electrochemistry. The through-line is particle-level explanation: nearly every question ends in "explain why", and the answer must talk about particles, forces and energy.

Two ideas carry the most marks. Intermolecular forces explain boiling points, solubility and chromatography. Le Châtelier's principle explains every shift in an equilibrium. Learn both properly and a large part of the paper opens up.

A calculation without units and significant figures is an incomplete answer.

The notes follow the nine CED units, each with worked examples and the relationships given on the exam's equation sheet. Past FRQs and scoring guidelines are in the library — chemistry's long questions pay for explaining behaviour at the particle level, so the model answers are written in that register.

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Past Papers
  • 1

    Atomic Structure and Properties

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    • 1.1 Moles and Molar Mass
    • 1.2 Mass Spectra of Elements
    • 1.3 Elemental Composition of Pure Substances
    • 1.4 Composition of Mixtures
    • 1.5 Atomic Structure and Electron Configuration
    • 1.6 Photoelectron Spectroscopy
    • 1.7 Periodic Trends
    • 1.8 Valence Electrons and Ionic Compounds
    • 1.8 Exam tips
  • 2

    Compound Structure and Properties

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    • 2.1 Types of Chemical Bonds
    • 2.2 Intramolecular Force and Potential Energy
    • 2.3 Structure of Ionic Solids
    • 2.4 Structure of Metals and Alloys
    • 2.5 Lewis Diagrams
    • 2.6 Resonance and Formal Charge
    • 2.7 VSEPR and Bond Hybridization
    • 2.7 Exam tips
  • 3

    Properties of Substances and Mixtures

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    • 3.1 Intermolecular and Interparticle Forces
    • 3.2 Properties of Solids
    • 3.3 Solids, Liquids, and Gases
    • 3.4 The Ideal Gas Law
    • 3.5 Kinetic Molecular Theory
    • 3.6 Deviation from the Ideal Gas Law
    • 3.7 Solutions and Mixtures
    • 3.8 Representations of Solutions
    • 3.9 Separation of Solutions and Mixtures
    • 3.10 Solubility
    • 3.11 Spectroscopy and the Electromagnetic Spectrum
    • 3.12 Properties of Photons
    • 3.13 The Beer-Lambert Law
    • 3.13 Exam tips
  • 4

    Chemical Reactions

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    • 4.1 Recognizing a Chemical Reaction
    • 4.2 Net Ionic Equations
    • 4.3 Three Ways to Represent a Reaction
    • 4.4 Physical Changes versus Chemical Changes
    • 4.5 Stoichiometry
    • 4.6 Introduction to Titration
    • 4.7 Types of Chemical Reactions
    • 4.8 Acid-Base Reactions
    • 4.9 Oxidation-Reduction (Redox) Reactions
    • 4.9 Exam tips
  • 5

    Kinetics

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    • 5.1 How Fast a Reaction Goes
    • 5.2 Writing the Rate Law
    • 5.3 Concentration Over Time
    • 5.4 The Steps a Reaction Really Takes
    • 5.5 Why Collisions Do or Do Not React
    • 5.6 Reading an Energy Profile
    • 5.7 The Sequence of Steps
    • 5.8 Finding the Rate Law From a Mechanism
    • 5.9 When the First Step Is Fast
    • 5.10 Energy Profiles for Many Steps
    • 5.11 How Catalysts Speed Things Up
    • 5.11 Exam tips
  • 6

    Thermochemistry

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    • 6.1 Endothermic and Exothermic Processes
    • 6.2 Energy Diagrams
    • 6.3 Heat Transfer and Thermal Equilibrium
    • 6.4 Heat Capacity and Calorimetry
    • 6.5 Energy of Phase Changes
    • 6.6 Introduction to Enthalpy of Reaction
    • 6.7 Bond Enthalpies
    • 6.8 Enthalpy of Formation
    • 6.9 Hess's Law
    • 6.9 Exam tips
  • 7

    Equilibrium

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    • 7.1 Introduction to Equilibrium
    • 7.2 Direction of Reversible Reactions
    • 7.3 The Reaction Quotient and Equilibrium Constant
    • 7.4 Calculating the Equilibrium Constant
    • 7.5 Magnitude of the Equilibrium Constant
    • 7.6 Properties of the Equilibrium Constant
    • 7.7 Calculating Equilibrium Concentrations
    • 7.8 Representations of Equilibrium
    • 7.9 Introduction to Le Chatelier's Principle
    • 7.10 The Reaction Quotient and Le Chatelier's Principle
    • 7.11 7.12 Introduction to Solubility Equilibria
    • 7.11 7.12 Exam tips
  • 8

    Acids and Bases

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    • 8.1 Introduction to Acids and Bases
    • 8.1 The Autoionization of Water
    • 8.2 pH and pOH of Strong Acids and Bases
    • 8.3 Weak Acid and Base Equilibria
    • 8.4 Acid-Base Reactions and Buffers
    • 8.5 Acid-Base Titrations
    • 8.6 Molecular Structure of Acids and Bases
    • 8.7 pH and pKa
    • 8.8 Properties of Buffers
    • 8.9 The Henderson-Hasselbalch Equation
    • 8.10 Buffer Capacity
    • 8.11 pH and Solubility
    • 8.11 Exam tips
  • 9

    Thermodynamics and Electrochemistry

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    • 9.1 Introduction to Entropy
    • 9.2 Absolute Entropy and Entropy Change
    • 9.3 Gibbs Free Energy and Thermodynamic Favorability
    • 9.4 Thermodynamic and Kinetic Control
    • 9.5 Free Energy and Equilibrium
    • 9.6 Free Energy of Dissolution
    • 9.7 Coupled Reactions
    • 9.8 Galvanic and Electrolytic Cells
    • 9.9 Cell Potential and Free Energy
    • 9.10 Cell Potential Under Nonstandard Conditions
    • 9.11 Electrolysis and Faraday's Law
    • 9.11 Exam tips

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