Study guides
Chemistry study guides
Plain-language chemistry guides for high school and AP students. Each one explains the idea, works through real problems with every unit shown, lists the mistakes teachers see most, and ends with practice questions you can check. Every numeric answer on these pages was recomputed in code from IUPAC atomic weights.
Updated
- 1How to balance chemical equationsBalance chemical equations step by step: count atoms, change only coefficients, handle fractions and polyatomic ions. 4 worked examples and 5 practice problems.
- 2Types of chemical reactionsThe 5 types of chemical reactions: synthesis, decomposition, single and double replacement, combustion. How to spot each, predict products, and practice.
- 3The mole and molar massWhat a mole is, how to find molar mass, and how to convert grams, moles and particles. Worked examples with units, common mistakes and 5 practice problems.
- 4Stoichiometry: how much reacts and how much formsLearn stoichiometry in three steps: grams to moles, mole ratio, moles to grams. Worked examples with every unit shown, common mistakes and 5 practice problems.
- 5How to find the limiting reactantFind the limiting reactant and excess reactant step by step, then the product amount and leftover. Worked examples in moles and grams plus 5 practice problems.
- 6How to calculate percent yieldHow to calculate percent yield: find the theoretical yield with stoichiometry, then divide actual by theoretical. Worked examples and 5 practice problems.
- 7Molarity and dilutionMolarity is moles of solute per liter of solution. Learn the molarity formula, M1V1 = M2V2 for dilutions, worked examples with units and 5 practice problems.
- 8The ideal gas law: PV = nRTUse the ideal gas law PV = nRT and the combined gas law. Which R to use, converting to kelvins, worked examples with units and 5 practice problems with answers.
- 9How to write electron configurationsWrite electron configurations step by step: filling order, noble gas shorthand, ions, Hund's rule and the Cr and Cu exceptions, plus 5 practice questions.
- 10Periodic trendsPeriodic trends made simple: atomic radius, ionization energy, electronegativity and ion size, the reason for each, real data and 5 practice questions.
- 11Ionic vs covalent bondsIonic vs covalent bonds: electron transfer vs sharing, the electronegativity difference rule, a properties table, ionic formulas and 5 practice questions.
- 12How to draw Lewis structuresDraw Lewis structures in 6 steps: count valence electrons, connect atoms, fill octets, add multiple bonds, check formal charge. Plus 5 practice questions.
- 13VSEPR theory and molecular shapesPredict molecular shape with VSEPR: count electron groups and lone pairs, read the shapes chart, find bond angles and polarity, then try 5 practice questions.
- 14Acids, bases and pHAcids, bases and the pH scale: pH = -log[H3O+], pOH, strong vs weak acids, conjugate pairs and pH significant figures, with examples and 5 practice problems.
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