Explore structured chemistry courses, solved problems, simulations and Python activities.
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.
Five laws of chemical combination led Dalton to the atom. Use them, find atomic and molecular masses, and meet the mole: the chemist's way of counting particles by weighing them.
Sort matter into elements, compounds and mixtures, and measure it in SI units. Learn to write numbers in scientific notation, to keep the right significant figures, and to change units without mistakes.
Bohr's circles work for hydrogen, and they fail for every other atom. The better picture is a cloud of probability. In this course we meet the waves of matter, the uncertainty principle, the four quantum numbers and the shapes of orbitals. Then we use three rules to write the electron configuration of any atom, and we explain the odd cases, such as chromium and copper.
Heat an element in a flame, and it gives out its own colours. Hydrogen gives a few sharp lines, and not a smooth rainbow. In this course we learn how light behaves as a wave and as a stream of particles, how the lines of hydrogen are counted, and how Bohr explained them with energy levels, with numbers that you can check.
How do you weigh something that no one has ever seen? Thomson, Millikan and Rutherford did it with glowing tubes, oil drops and a thin gold foil. In this course we see how the electron, the proton and the neutron were found, how big the nucleus is, and how a mass spectrometer finds the isotopes of an element.
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Harder mole problems of the kind JEE and NEET set: 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 and take a JEE Advanced style test.