Fluorine: chemical bonding 134 reactivity

Fluorine (F) is one of the most reactive elements and forms chemical bonds with almost all the other elements (with the exception of helium and neon), though it takes higher temperatures to react with noble metals, such as gold, platinum, and palladium. Fluorine can even react with an inert gas (krypton) ... 

In this chapter, we examine the quantum-mechanical model of the atom, a model that explains the strange behavior of electrons. In particnlar, we focus on how the model describes electrons as they exist within atoms, and how those electrons determine the chemical and physical properties of elanents. Yon have already learned mnch about those properties. You know, for example, that some elanents are metals and that others are nomnetals. You know that the noble gases are chanically inert and that the alkali metals are chemically reactive. You know that sodinm tends to form 1+ ions and that fluorine tends to form 1 - ions. But we have not explored why. The quantum-mechanical model explains why. In doing so, it explains the modem periodic table and provides the basis for our understanding of chemical bonding. 

In a molecule, fluorine atoms influence bond energies, electronic distribution, acidity, hydrogen bonds, steric interactions, and the stability of intermediate entities in a transformation. These factors, which have great influence on chemical reactivity, are examined. 

Modifications of the chemical reactivity generated by the presence of fluorine atoms in a molecule are connected to three main factors the strength of the C— F bond, the electron-withdrawing character of the fluorinated substituents, and the possible loss of a fluoride ion or of HF in the processes of )S-elimination. On these bases and taking into account the ability of fluoro-substituents to sterically or electronically mimic other... 

Organo-fluorine compounds have a diverse, often unanticiptated chemistry. The chemical behavior of fluorinated species is much more comprehensible if the effects of fluorination on reactivity are rationalized. It is the effect of fluorine on reactive intermediates that in turn governs the outcome of reactions. The principal properties of fluorine which have the most profound influence on bonding and, therefore, reactivity are the pronounced electronegativity of fluorine1 and its associated low polarizability,2 the availability of three nonbonded electron pairs, and the excellent overlap that is possible between the 2s and 2p orbitals of fluorine and those of carbon.3... 

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