Explore structured chemistry courses, solved problems, simulations and Python activities.
Why some salt solutions are acidic or basic, buffer solutions and how they resist a change in pH, the solubility product and the common ion effect.
Arrhenius, Bronsted-Lowry and Lewis acids and bases, conjugate pairs, the ionisation of water, the pH scale, and the ionisation constants of weak acids and bases.
Dynamic equilibrium in physical and chemical changes, the law of mass action, Kc and Kp and how they are linked, the reaction quotient, finding equilibrium amounts, and Le Chatelier's principle.
What makes a change spontaneous, entropy and the second law, Gibbs energy and the sign of ΔG, the effect of temperature, and the link between ΔG and equilibrium.
Enthalpy and how it differs from internal energy, heat capacity and calorimetry, standard enthalpies of reaction, formation and combustion, bond enthalpies, and Hess's law.
Systems and surroundings, state functions, work and heat, internal energy and the first law of thermodynamics, with work done by an expanding gas.
How atomic orbitals combine into bonding and antibonding molecular orbitals, the energy order for second-period molecules, bond order and magnetism, and the hydrogen bond.
VSEPR theory and the shapes it predicts, with lone pairs that squeeze the angles; valence bond theory, sigma and pi bonds; and hybridisation from sp to sp3d2.
The octet rule and Lewis structures, formal charge and its limits, the ionic bond and lattice enthalpy, and the bond length, angle, enthalpy and order that describe any bond.
How the size of atoms and ions, the ionisation enthalpy, the electron gain enthalpy and the electronegativity change across a period and down a group, and how they decide valence and reactivity.
From Dobereiner's triads to Mendeleev's gaps and Moseley's atomic numbers: how the periodic table was built, how new elements are named, and how the s, p, d and f blocks follow from electron configurations.
Find a compound's formula from its percentage composition, work out how much of each substance a reaction needs and makes, find the limiting reagent, and express the strength of a solution.
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The calculations that JEE, AP Chemistry and A-Level Chemistry set most: degree of dissociation from vapour density, simultaneous equilibria, pH of mixtures and very dilute solutions, polyprotic acids, and precipitation with Ksp, with a full timed paper.
The calculations that JEE, AP Chemistry and A-Level Chemistry ask most: work in reversible and irreversible expansions, Born-Haber and Hess cycles, bond enthalpies, and ΔG from ΔH and ΔS, with a full timed paper.
The hard questions of the chapter: dipole moments and molecular shape, tricky Lewis structures and formal charges, back bonding and bridges, and comparing bond lengths and energies, with a full paper.
Harder mole problems at the level of JEE, NEET, AP Chemistry and A-Level Chemistry: mixtures and average molar mass, reactions in sequence, yield and purity, and titrations, each worked step by step, with a full timed paper.
Why can an electron in an atom never be at rest? Why does oxygen lose an electron more easily than nitrogen, although its nucleus pulls harder? In this course we read two ideas that the main chapter only touches: the electron in a box, and the shielding of the nucleus by the inner electrons. Then we solve harder problems at the level of JEE Advanced, AP Chemistry and A-Level Chemistry, and take an advanced timed test.