Polarization and Reactivity: It is to be expected that the fairness with which electrons are shared should vary continu- ously between the sharing of the idealized covalent bond and the “winner takes all” of the ionic bond. Some of the other atoms in covalently bonded organic carbon com- pounds will always want more than a fair share of the available electrons-e.g., nitrogen, oxygen, fluorine, chlorine and sulfur-whereby they themselves tend to acquire an electronegative character, and their carbon neighbors, an electropositive character. This tendency does not nor- mally lead to ion formation. It is called polarization, and makes individual atoms within a molecule more susceptible to electrostatic interaction with atoms of the opposite characteristic whenever they are in close proximity. Many reactions be- tween different covalently bonded materi- als are initiated by polarization, and may be completed by formation of products with quite different bonding (electron distribution) than the original reactants. The actual outcome of reactions often depends on complex energy consider- ations.