IB Chemistry – Topic Summaries (SL & HL)
A free overview of IB Diploma Chemistry organised by the two strands of the current course: Structure and Reactivity. HL students go further in each topic; the key ideas below apply to both SL and HL.
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1. Structure 1 – Models of the particulate nature of matter
Matter is made of particles whose arrangement and energy explain states and changes of state. Atoms contain protons, neutrons and electrons; isotopes differ in neutrons and are detected by mass spectrometry. Electrons occupy energy levels and orbitals, shown by emission spectra and electron configurations. The mole connects particle counts with measurable masses, volumes and concentrations.
Key terms: kinetic theory, isotope, mass spectrometry, emission spectrum, orbital, electron configuration, mole, ideal gas
2. Structure 2 – Models of bonding and structure
Ionic, covalent and metallic bonding explain the properties of substances. Covalent molecules have shapes predicted by VSEPR and polarity from electronegativity; intermolecular forces decide boiling points and solubility. Giant covalent, ionic and metallic lattices behave differently, and materials such as alloys and polymers are chosen by matching structure to use.
Key terms: ionic lattice, covalent bond, VSEPR, polarity, intermolecular forces, metallic bonding, alloy, polymer
3. Structure 3 – Classification of matter
The periodic table groups elements with similar configurations and shows trends in radius, ionization energy and electronegativity. Organic compounds are classified into homologous series by functional group and named systematically, and isomers share a formula but differ in structure.
Key terms: periodic trends, periodicity, homologous series, functional group, IUPAC naming, isomer
4. Reactivity 1 – What drives chemical reactions?
Reactions transfer energy as heat. Enthalpy changes are measured by calorimetry and calculated with Hess’s law and bond enthalpies. Entropy and Gibbs energy decide whether a reaction is spontaneous. Burning fuels releases energy but also carbon dioxide, linking chemistry to energy choices.
Key terms: enthalpy, calorimetry, Hess’s law, bond enthalpy, entropy, Gibbs energy, combustion
5. Reactivity 2 – How much, how fast and how far?
Stoichiometry predicts amounts of reactants and products and percentage yield. Reaction rates depend on concentration, temperature, surface area and catalysts, explained by collision theory and activation energy. Many reactions are reversible and reach dynamic equilibrium, described by the equilibrium constant and shifted according to Le Châtelier’s principle.
Key terms: stoichiometry, limiting reagent, rate, collision theory, activation energy, equilibrium constant, Le Châtelier
6. Reactivity 3 – What are the mechanisms of chemical change?
Most reactions transfer protons, electrons or electron pairs. Acids and bases transfer protons and are compared with pH and strength. Redox reactions transfer electrons and drive electrochemical cells and electrolysis. Organic reactions such as substitution, addition and elimination proceed through radical, nucleophilic and electrophilic mechanisms.
Key terms: Brønsted–Lowry, pH, redox, oxidation state, electrochemical cell, nucleophile, electrophile, substitution
These summaries are written by Dabour Hub from the published course outline. Full notes, diagrams, quizzes and question banks are available to registered students.
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