Chemistry explained: every letsBug chemistry post

Atoms, electron shells and mixtures explained step by step, with diagrams. Each post goes with a letsBug video and ends with practice questions.

What Is Inside an Atom? Protons, Neutrons and Electrons: What is inside an atom? Protons, neutrons and electrons: their charges and masses, atomic and mass number, isotopes and electron shells.
Why Are Noble Gases Unreactive? Electron Shells Explained: Why are noble gases unreactive? A full outer shell. Plus the electronic configuration of the first 20 elements in one clear table.
Is Air a Mixture or a Compound? Separating Mixtures: Is air a mixture or a compound? A mixture: its gases aren't chemically combined. Learn filtration, distillation and chromatography, with Rf values.
Why is chlorine's atomic mass 35.5? Isotopes explained: Why is chlorine's atomic mass 35.5? It's a weighted mean of chlorine-35 and chlorine-37. Learn isotopes and how to calculate relative atomic mass.
Aluminium oxide formula: why Al2O3? Valency explained: Aluminium oxide formula: why is it Al2O3, not AlO? Learn valency, ion charges and the criss-cross method, with brackets and practice questions.
Why do ionic compounds have high melting points?: Why do ionic compounds have high melting points? Learn ionic bonding: electron transfer, dot-and-cross diagrams, the giant lattice and conductivity.
How to draw dot and cross diagrams for covalent bonds: How to draw dot and cross diagrams for covalent bonds: a counting check, lone pairs, double and triple bonds, and why methane boils at about −162 °C.