The Model Kit

Axiom One: The rows of the periodic table describes the filling of electrons into valence shells around the nucleus, with each element having a unique electron configuration in its hypothetical isolated ‘ground state’.

Axiom Two: Atoms in a molecule form covalent bonds as to seek a filled valence shell of electrons for each atom in the molecule.

Axiom Three: Atoms in a molecule also form covalent bonds as to seek a neutral charge balance (protons versus electrons) in the vicinity of each atom in the molecule.

Much of our understanding of molecular structure and chemical reactivity can be derived from these basic principles.