Chemistry Study Guides

Every guide is written for students: plain language, worked examples, the common mistakes to dodge, and a link to the calculator that practises the skill. Start with whatever your class is covering this week.

Periodic Table Explained: Groups, Periods & How to Read ItThe periodic table lists all 118 elements in 18 groups and 7 periods. Learn how it is organised, what each tile means, and how to read groups and periods.5 sections · 5 FAQs

Molar Mass: Definition and How to Calculate ItWhat is molar mass, and how do you find it? Add up the atomic masses in a formula to get grams per mole. Worked examples for H2O, glucose, Ca(OH)2 and NaCl.4 sections · 6 FAQs

How to Balance Chemical EquationsLearn to balance chemical equations step by step using the counting method, with combustion and metal-acid examples plus the most common mistakes.3 sections · 3 FAQs

Electron Configuration ExplainedUnderstand electron configurations: shells, s/p/d/f subshells, the Aufbau principle, Pauli exclusion, Hund's rule, noble gas shorthand and famous exceptions.5 sections · 3 FAQs

Periodic Trends ExplainedMaster the four main periodic trends — atomic radius, ionization energy, electronegativity and metallic character — with directions, reasons and examples.6 sections · 3 FAQs

Atomic Number vs Atomic MassAtomic number counts protons; atomic mass averages isotope masses. Learn the difference, what mass number means, and how to use all three correctly.4 sections · 3 FAQs

Metals, Nonmetals, and MetalloidsCompare metals, nonmetals and metalloids: physical and chemical properties, where each sits on the periodic table, and examples of everyday uses.4 sections · 3 FAQs

Valence Electrons ExplainedWhat valence electrons are, how to count them from group numbers or electron configurations, and why they control bonding and reactivity.3 sections · 3 FAQs

pH and pOH ExplainedUnderstand the pH and pOH scales: the formulas pH = −log[H⁺] and pH + pOH = 14, worked examples, and why each pH step means 10× the acidity.4 sections · 3 FAQs

Molarity and Dilution ExplainedLearn molarity (M = mol/L) and dilution (C₁V₁ = C₂V₂) with worked examples, lab-style problems and the unit mistakes to avoid.3 sections · 3 FAQs

Stoichiometry Step-by-StepA clear method for stoichiometry: balance the equation, convert to moles, apply the mole ratio, convert back. Includes full worked examples.4 sections · 3 FAQs

Common Chemistry Formulas for StudentsOne-page reference of essential chemistry formulas: moles, molarity, dilution, pH, gas laws, percent yield and more — each with units and an example.5 sections · 2 FAQs

How to Find Protons, Neutrons, and ElectronsFind protons, neutrons and electrons from the periodic table: protons = atomic number, neutrons = mass number − atomic number, electrons adjust with charge.4 sections · 3 FAQs

Groups and Periods on the Periodic TableGroups are columns sharing valence electrons and chemistry; periods are rows sharing shell count. Learn the named families and how to use both.3 sections · 3 FAQs

How to Read Chemical FormulasDecode any chemical formula: element symbols, subscripts, parentheses, coefficients and hydrate dots — with H2O, Ca(OH)2 and CuSO4·5H2O examples.3 sections · 3 FAQs

What Are Isotopes?Isotopes are atoms of the same element with different neutron counts. Learn notation, why atomic masses are decimals, and real uses from dating to medicine.4 sections · 4 FAQs

What Are Ions?Ions are charged atoms formed by losing or gaining electrons. Learn cations vs anions, how to predict charges from the periodic table, and polyatomic ions.4 sections · 3 FAQs

Oxidation Numbers ExplainedLearn the oxidation number rules — free elements are 0, oxygen −2, hydrogen +1 — and use them to solve KMnO₄, SO₄²⁻ and more, step by step.4 sections · 3 FAQs

Limiting Reactants ExplainedThe limiting reactant runs out first and caps the product. Learn the divide-by-coefficient method, theoretical yield and excess with worked examples.3 sections · 3 FAQs

Ideal Gas Law ExplainedUnderstand PV = nRT: what each variable means, choosing the right R, kelvin conversions, worked examples, and when the ideal gas law breaks down.4 sections · 3 FAQs

Ionic vs Covalent BondsIonic bonds transfer electrons between a metal and a nonmetal; covalent bonds share them between nonmetals. Compare properties, examples and how to tell them apart.5 sections · 4 FAQs

Molarity vs MolalityMolarity is moles per litre of solution; molality is moles per kilogram of solvent. Learn when each is used, why temperature matters, and how to calculate both.4 sections · 3 FAQs