Atoms and Elements
How the atom was found, taken apart and finally explained: from combining weights and Rutherford scattering to orbitals, periodic trends and the chemical bond.
The atomic hypothesis
The quantitative evidence that matter comes in discrete units, from the laws of combining weights to the counting of Avogadro's number.
Probing the atom
How the electron, the nucleus and the neutron were found, and how scattering experiments measured a structure nobody could see.
The quantum atom
Why the nuclear atom cannot work classically, and the quantum description that replaced it, from Bohr's orbits to the shapes of orbitals.
Many-electron atoms
How electrons arrange themselves once there is more than one, through exclusion, shielding and the order in which orbitals fill.
Periodicity
Why the properties of the elements repeat, and how radius, ionisation energy and electronegativity follow from effective nuclear charge.
Chemical bonding
What happens when atoms meet, from ionic lattices and Lewis structures to hybrid orbitals and the molecular orbitals that explain why oxygen is magnetic.