Rationalization of Chemical

The concept of aromaticity is important in the rationalization of chemical reactivity and, by extension, in the understanding of biological properties and the prediction of technological behavior. In heteroaromatic chemistry, the degree of aromaticity is of particular importance in guiding our understanding of aromaticity. 

These are extensions of Lewis dot structures, where bonding electrons associated with each bond are shown as dots. In our simple structures, bonding is associated with eight electrons in the valence shell of the atom, unless it is hydrogen, when two electrons are required for bonding. Whilst we have almost completely abandoned putting in electron dots for bonds, we still routinely show some pairs of electrons not involved in bonding (lone pairs) because these help in our mechanistic rationalizations of chemical reactions. 

Chemistry is an experimental science, and to rationalize our observations we gradually develop and invoke a number of rules and principles. Theories may have to change as scientific data increase, and as old principles cease to explain the facts. All of the foregoing description of atomic and molecular orbitals is a hypothesis for atomic and molecular structure supported by experimental data. So far, the description meets most of our needs and provides a good rationalization of chemical behaviour. However, it falls short in certain ways, and we have to invoke a further modification to explain the facts. Here are three observations based upon sound experimental evidence, which are not accommodated by the above description of bonding ... 

This background now allows us to more fully appreciate the uniqueness of Dalton s contribution, when, in the period 1803-1808, he shifted, for the first time, the focus of chemical atomism from the atomic parameters of shape and interparticle forces to a consideration of relative atomic weights, with a concomitant emphasis on characterizing the chemical composition of individual species rather than on the classification and rationalization of chemical reactions. 

The introduction of membrane contactors in industrial cycles might represent an interesting way to realize the rationalization of chemical productions in the logic of the process intensification. Membrane contactors are, in fact, highly efficient systems for carrying out the mass transfer between phases and achieving high removals. They also present lower size than conventional apparatus. Commercial applications are already present (e.g., the electronics industry or bubble-free carbonation lines), however, some critical points must be still overcome and several are the research efforts needed for their further implementation at industrial level, as summarized below ... 

Pauling rationalization of chemical bonding in solids Perovskite type polarization in crystals... 

Resonance structures extend the utility of Lewis theory in explaining electron delocalization In certain structures. Resonance structures are an integral part of Lewis theory that allows rationalization of chemical and physical properties In a simple and predictive manner. Lewis theory follows the Idea of electron pair bonds, and a typical example where resonance Is used Is for describing the cyclic structure of benzene,... 

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