In addition to the Lewis, VSEPR, valence bond, molecular orbital, and various acid-base models that are important for understanding chemical structure and bonding, a number of general principles are useful for understanding trends in the properties of the main group elements. These include:
1. The Periodic Law and Periodic Table, most notably the ordering of elements with similar chemical properties by group, the metal-nonmetal distinction, and the second row uniqueness principle.
2. Periodic trends in atomic properties, most notably atomic radii, ionization energy, electron affinity, and electronegativity, on account fo which there are diagonal relationships between elements in the periodic table.
3. Periodic trends in elements' redox properties, which can be helpfully illuminated with the aid of Latimer, Frost, and Pourbaix diagrams.
The remaining pages of this section will outline these principles.
Stephen Contakes, Westmont College