Where electrons live
An atom is almost entirely empty space. So where do its electrons actually live?
The orbiting-planet picture of the atom collapses in sixteen picoseconds. What replaces it: standing waves, quantized energies, and electron clouds you can rotate with your mouse.
The filling order
Why does a higher shell start filling before the one below it is full?
With many electrons, three seating rules decide who goes where. Watch the energy ladder's rungs drift and cross as the nucleus grows, and see exactly why 4s fills before 3d.
The table is a map
Why is the periodic table that strange, lopsided shape?
The periodic table's odd shape is the filling order made visible. Build it row by row, then watch one number, the pull felt by outer electrons, drive every trend across it.
One continuum, not three bonds
What holds two atoms together, and why do some bonds share while others transfer outright?
Covalent, polar, ionic: textbooks present three kinds of bond. There is one, with a dial. Drag the tug-of-war and morph a shared electron cloud into a full transfer.
Building molecules
Why is water always H₂O, never HO or H₃O?
Valence electrons become a notation, the notation becomes a tool. Assemble real molecules dot by dot, with the octet rule checking your work.
Shapes & stickiness
Why does water bead up, and why do molecules take the 3D shapes they do?
Why molecules take 3D shapes (electron domains shoving each other), and why water is so strange (hydrogen bonding). Coming next.