Essential Chemistry for Biology Videos to Watch Matter, Elements, Compounds - Video 1 Atoms - Video 2 Electrons, Orbitals, & Valence - Video 3 Covalent Bonding - Video 4 Ionic Bonding - Video 5 Hydrogen Bonding - Video 6 Solutions & Concentrations - Video 7 pH (part 1) - Video 8 pH (part 2) - Video 9 Oxidation & Reduction - Video 10 NAD+ / NADH, An Electron Carrier - Video 11