We learn of the various quantum numbers that describe the size and shape of the energy levels that electrons have inside atoms. Then Louis de Broglie proposes that, just as light has particle characteristics, matter (including electrons) have wave characteristics, which Davisson, Germer, and Thomson show is true. From this, we find that electron waves can fit around atoms only in certain energies. Heitler and London model the smallest molecule, dihydrogen, using quantum-mechanical principles. Linus Pauling takes some general ideas from quantum mechanics, and applies them to chemical bonding.Support the show Support my podcast at https://www.patreon.com/thehistoryofchemistry Tell me how your life relates to chemistry! E-mail me at steve@historyofchem.com Get my book, O Mg! How Chemistry Came to Be, from World Scientific Publishing, https://www.worldscientific.com/worldscibooks/10.1142/12670#t=aboutBook ...