Are you looking to excel in your AP Chemistry course and exam? Look no further! Our comprehensive cheat sheet provides all the critical information you need to master this challenging subject.
Statistics You Can’t Ignore
Over 190,000 students took the AP Chemistry exam in 2022.
55% of students scored a 3 or higher, qualifying them for college credit.
The average score on the exam was 2.88.
Atomic Structure and Properties
Atomic Structure
Atomic number (Z): Number of protons in the nucleus
Mass number (A): Number of protons + neutrons in the nucleus
Isotopes: Atoms of the same element with different numbers of neutrons
Periodic Trends
Metals: Generally shiny, ductile, malleable, and good conductors
Nonmetals: Generally dull, brittle, and poor conductors
Ionization energy: Energy required to remove an electron from an atom
Electron affinity: Energy released when an electron is added to an atom
Chemical Bonding
Ionic Bonding
Formed between a metal and a nonmetal
Metal loses electrons to form cations, which are attracted to anions formed by the nonmetal
Covalent Bonding
Formed between two nonmetals
Atoms share electrons to form stable covalent bonds
Molecular Geometry
Linear: 180° bond angle
Trigonal planar: 120° bond angle
Tetrahedral: 109.5° bond angle
States of Matter
Gas
Particles have high kinetic energy and are widely spaced
Assumes the shape and volume of its container
Can be compressed or expanded
Liquid
Particles are closer together than in a gas but still have high kinetic energy
Assumes the shape of its container but has a fixed volume
Can be poured or pumped
Solid
Particles are closely packed with low kinetic energy
Has a definite shape and volume
Cannot be compressed or expanded
Equilibrium
Chemical Equilibrium
Reversible reaction where the forward and reverse reactions occur at equal rates
Equilibrium constant (Keq): Numerical value that describes the extent of the reaction
Le Chatelier’s Principle
Predicts how chemical equilibrium will shift in response to changes in conditions (e.g., temperature, pressure, concentration)
Acids, Bases, and Buffers
Acids
Donate protons (H+)
Can lower the pH of a solution
Bases
Accept protons (H+)
Can raise the pH of a solution
Buffers
Solutions that resist changes in pH when small amounts of acid or base are added
Thermodynamics
First Law of Thermodynamics
Energy cannot be created or destroyed, only transferred or transformed
Second Law of Thermodynamics
Entropy (disorder) of the universe always increases
Gibbs Free Energy
Predicts the spontaneity of a reaction at constant temperature and pressure:
** ΔG < 0: Spontaneous
** ΔG > 0: Nonspontaneous
** ΔG = 0:** Equilibrium
Kinetics
Reaction Rates
Rate law: Equation that expresses the dependence of the reaction rate on the concentration of reactants
Activation energy: Minimum energy required for a reaction to occur
Influencing Factors
Temperature
Concentration of reactants
Catalyst presence
Surface area
Electrochemistry
Redox Reactions
Involve the transfer of electrons between species
Oxidation: Loss of electrons
Reduction: Gain of electrons
Electrochemical Cells
Convert chemical energy into electrical energy or vice versa
Galvanic cells: Produce electricity
Electrolytic cells: Consume electricity
Calculations and Applications
Stoichiometry
Mole ratio: Converted units to compare amounts of reactants and products
Limiting reactant: Reactant that is completely consumed in a reaction
Gas Laws
Ideal gas law: PV = nRT
Combined gas law: (P1V1)/T1 = (P2V2)/T2
Solution Chemistry
Molarity: Moles of solute per liter of solution
Colligative properties: Properties that depend on the concentration of the solute, not its identity
Osmosis: Movement of water across a semipermeable membrane
Common Mistakes to Avoid
Confusing molarity with molality
Not balancing chemical equations
Ignoring units in calculations
Misinterpreting Le Chatelier’s principle
Applications of AP Chemistry
Nanotechnology: Manipulating matter at the atomic and molecular scale Green chemistry: Designing chemical processes that minimize environmental impact Biotechnology: Using chemistry to advance medical treatments and develop new drugs Materials science: Creating new materials with tailored properties
