Chapter 4 Study Guide How to write electron configurations Know the family name based on the group number on the periodic table and their properties. Know the most reactive element (F) Know which family is most unreactive and why Know the models of the atom in the order they were developed Know the following people: Democritus Dalton Thomson Millikan Rutherford Einstein (photoelectric effect) Planck (quantum nature of energy) Heisenberg (uncertainty theory) Bohr (planetary model) De broglie (electrons are both a wave and a particle)