CH1: Matter and Measurement

States of Matter and Kinetic Molecular Theory

The states of matter—solid, liquid, and gas—are defined by the arrangement and movement of particles, as described by the kinetic molecular theory.

• Solids: Particles are closely packed in a fixed structure; they vibrate but do not move freely.

• Liquids: Particles are close but can move past each other, allowing liquids to flow.

• Gases: Particles are far apart and move rapidly, filling the container's volume.

Kinetic molecular theory explains these differences based on particle energy and interactions.

Classification of Matter

• Elements: Pure substances consisting of one type of atom (e.g., O2).

• Compounds: Substances composed of two or more elements chemically combined (e.g., H2O).

• Mixtures: Physical combinations of two or more substances.

  • Heterogeneous mixtures: Composition is not uniform (e.g., salad, sand in water).

  • Homogeneous mixtures (solutions): Uniform composition throughout (e.g., saltwater).

Physical vs. Chemical Change

• Physical change: Alters appearance or state, not composition (e.g., melting ice).

• Chemical change: Produces new substances with different properties (e.g., rusting iron).

Separation Techniques

• Filtration: Separates solids from liquids using a porous barrier.

• Distillation: Separates substances based on differences in boiling points.

• Chromatography: Separates components based on their movement through a medium.

Measurement and SI Units

• SI base units: Standard units for measurement (e.g., meter for length, kilogram for mass, second for time, kelvin for temperature, mole for amount of substance).

• Temperature conversion:

• Density:

Accuracy, Precision, and Significant Figures

• Accuracy: Closeness to the true value.

• Precision: Reproducibility of measurements.

• Percent error:

• Significant figures: Digits in a measurement that are known with certainty plus one estimated digit; rules govern their use in calculations.

CH2: Atoms, Molecules, and Ions

Atomic Theory and Structure

• Atomic theory: All matter is composed of atoms, which are indivisible in chemical processes.

• Cathode ray tube experiment: Led to the discovery of the electron by J.J. Thomson.

• Nuclear model: Atom has a small, dense, positively charged nucleus (Rutherford's gold foil experiment).

• Subatomic particles: Protons (+), neutrons (0), electrons (−).

Atomic Number, Mass Number, and Isotopes

• Atomic number (Z): Number of protons in the nucleus.

• Mass number (A): Total number of protons and neutrons.

• Isotopes: Atoms of the same element with different numbers of neutrons.

• Average atomic mass: Weighted average of isotopic masses.

Periodic Table and Types of Elements

• Groups: Vertical columns with similar properties (e.g., alkali metals, halogens).

• Types of elements: Metals, nonmetals, metalloids.

Compounds: Ionic and Covalent

• Ionic compounds: Formed from metals and nonmetals; transfer of electrons; high melting points; conduct electricity when molten or dissolved.

• Covalent compounds: Formed from nonmetals; sharing of electrons; lower melting points; do not conduct electricity.

• Formulas and names: Use systematic rules for naming and writing formulas.

• Acids: Compounds that release H+ ions in solution; named based on anion (e.g., HCl = hydrochloric acid).

CH3: Stoichiometry

Chemical Equations and Balancing

• Chemical equation: Represents a chemical reaction with reactants and products.

• Balancing equations: Ensures the same number of each atom on both sides.

• States of matter: Indicated as (s), (l), (g), (aq).

Percent Composition and Formulas

• Percent composition:

• Empirical formula: Simplest whole-number ratio of atoms.

• Molecular formula: Actual number of atoms; multiple of empirical formula.

• Combustion analysis: Used to determine empirical/molecular formulas from combustion products.

Mole Concept and Conversions

• Mole: particles (Avogadro's number).

• Molar mass: Mass of 1 mole of a substance (g/mol).

• Conversions: Mass ↔ Moles ↔ Particles ↔ Volume (for gases at STP).

Stoichiometric Calculations

• Mole-to-mole conversions: Use coefficients from balanced equations.

• Limiting reactant: Reactant that is completely consumed, limiting the amount of product.

• Excess reactant: Reactant left over after the reaction.

• Theoretical yield: Maximum amount of product possible.

• Percent yield:

CH4: Reactions in Aqueous Solution

Solutions and Solvation

• Solution: Homogeneous mixture of two or more substances.

• Solute: Substance dissolved.

• Solvent: Substance doing the dissolving (often water).

• Solvation: Process of surrounding solute particles with solvent molecules; differs for ionic (dissociation into ions) and covalent (molecular dispersion) solutes.

Solubility Rules

• General guidelines for predicting solubility of ionic compounds in water.

• Top rules: Most nitrates (NO3−) and alkali metal salts are soluble.

Acids, Bases, and Neutralization

• Acid: Substance that donates H+ ions in solution.

• Base: Substance that donates OH− ions or accepts H+ ions.

• Neutralization reaction: Acid + base → salt + water.

Ionic Equations and Spectator Ions

• Complete ionic equation: Shows all strong electrolytes as ions.

• Net ionic equation: Shows only species that change during the reaction.

• Spectator ions: Ions that do not participate in the reaction.

Concentration and Solution Calculations

• Molarity (M):

• Ion concentration: Calculate based on dissociation of solute.

• Dilution equation:

Titration and Analytical Terms

• Titration: Technique to determine concentration of an unknown solution using a solution of known concentration.

• Aliquot: Measured sub-volume of a sample.

• Titrant: Solution of known concentration added to react with analyte.

• Equivalence point: Point at which stoichiometric amounts of reactants have reacted.

• End point: Point at which an indicator changes color, signaling completion of titration.

General Notes

• You will be provided with the AP Periodic Table and Equations Sheet during exams.

• Memorize the most important solubility rules, especially for common ions.