627 articles · 16 subjects
Chemistry Library
A free, growing library of original chemistry explainers, worked examples and practice questions for students and teachers, organised by topic.
Browse by topic
- 105Atomic StructureProtons, neutrons, electrons, orbitals and electron configurations — what atoms are made of and how their electrons are arranged.
- 39The Periodic Table & ElementsGroups, periods, trends and element records — how the table is organised and what it tells you.
- 135Bonding & Molecular StructureIonic, covalent and metallic bonds, molecular shapes, intermolecular forces and naming compounds.
- 12Moles & Chemical CalculationsThe mole, molar mass, formulas, yields and every calculation type you meet in a chemistry course.
- 4Chemical ReactionsReaction types, balancing equations, precipitation, combustion and predicting products.
- 82Acids, Bases & SaltspH, strong and weak acids, buffers, titrations, indicators and salt chemistry.
- 3Energy, Rates & EquilibriumThermochemistry, entropy, Gibbs energy, reaction kinetics and chemical equilibrium.
- 2Redox & ElectrochemistryOxidation numbers, redox equations, galvanic and electrolytic cells, batteries and corrosion.
- 6Gases, Liquids, Solids & SolutionsGas laws, phase changes, crystal structures, concentration units and colligative properties.
- 129Biochemistry & the Chemistry of LifeProteins, carbohydrates, lipids, DNA, enzymes and the chemistry happening inside living things.
- 7Nuclear Chemistry & RadioactivityRadioactive decay, half-life, fission, fusion, nuclear medicine and how new elements are made.
- 93Lab Techniques & AnalysisTitration, chromatography, spectroscopy, lab safety and how chemists identify substances.
- 2Environmental & Earth ChemistryAir, water, soil, climate, pollution, minerals and the chemistry of our planet.
- 1Materials & Industrial ChemistryHow chemicals are made at scale — metals, plastics, fertilisers, semiconductors and new materials.
- 6History & Famous ChemistsThe people, discoveries and experiments that built modern chemistry.
- 1Study Guides & TeachingExam preparation, revision strategies, common mistakes and ideas for teaching chemistry.
Latest additions
Amorphous vs Crystalline Solids: What's the Difference?
Crystalline solids have long-range order; amorphous solids don't. Compare melting, fracture, X-ray patterns and uses, with quartz vs glass as the key example.
Average Bond Enthalpies: A Reference Table with Explanations
A grouped table of average bond enthalpies in kJ/mol, from H–H to N≡N, with the reason behind each pattern and the difference from bond dissociation energy.
Which Substances Conduct Electricity, and Why?
Metals conduct, salt solution conducts, solid salt and sugar solution don't. One rule explains them all: you need charged particles that are free to move.
How Bonding Type Predicts Melting Point
Why methane melts at −182 °C and magnesium oxide near 2,850 °C: how ionic, molecular, giant covalent and metallic bonding set melting points.
How Bonding Type Predicts Solubility
Why salt dissolves in water but not in oil, why diamond dissolves in nothing, and how to predict solubility from ionic, molecular, giant covalent or metallic bonding.
The Bonding Triangle: Ionic, Covalent and Metallic as a Continuum
How the van Arkel–Ketelaar triangle places any binary substance between ionic, covalent and metallic bonding using two electronegativity numbers.
Chemical Bonding Exam Questions with Mark-Scheme Answers
14 exam-style chemical bonding questions (41 marks) on ionic, covalent and metallic bonding, shapes, polarity and forces, with a full mark scheme.
Bonding in Benzene: Kekulé vs the Delocalised Model
Why benzene's six C–C bonds are all the same length: the Kekulé structure, its three failures, the delocalised π ring, and the ~150 kJ/mol stability it brings.
Everything About Bonding in Water
From the O–H covalent bonds and 104.5° bent shape to hydrogen bonds, open ice and the 4 °C density peak: how bonding makes water so unusual.
Graphene and Carbon Nanotubes: Structure and Bonding
How one-atom-thick graphene and rolled-up carbon nanotubes are built from sp² carbon, and how their delocalised electrons explain their strength and conductivity.
Chelation and the Chelate Effect Explained
Why ligands that grip a metal with several donor atoms form far more stable complexes: entropy, ring size, EDTA, and chelation in water softening, medicine and biology.
Testing Conductivity to Classify Bonding
A safe low-voltage practical: test solids and solutions in a simple circuit, then use the results to sort each substance into ionic, covalent or metallic.