Lewis approach

The Lewis definitions of acids and bases provide for a more general view of acid-base reactions than either the Arrhenius or Br0nsted-Lowry pic ture A Lewis acid is an electron pair acceptor A Lewis base is an electron pair donor The Lewis approach incorporates the Br0nsted-Lowry approach as a subcategory m which the atom that accepts the electron pair m the Lewis acid is a proton... 

The Lewis approach also fails for the compound diborane, B2H6, a colorless gas that bursts into flame on contact with air. The problem is that diborane has only 12 valence electrons (3 from each B atom, 1 from each H atom), but for a Lewis structure, it needs at least 7 bonds, and therefore 14 electrons, to bind the 8 atoms together Diborane is an example of an electron-deficient compound, a compound with too few valence electrons to be assigned a valid Lewis structure. Valence-bond theory can account for the structures of electron-deficient compounds in terms of resonance, but the explanation is not straightforward. 

A major difference between the valence-bond theory of chemical bonding and molecular orbital theory is that the former assumes, like the Lewis approach, that the electrons in a bond are localized between the two... 

Also in the Taft-Lewis approach, the resonance R and polar effects I can be viewed as additive contributions to the overall electronic effect, defined as ... 

While the Bronsted acid/base terms specifically refer to proton donors and acceptors, respectively, the Lewis approach (named after G. N. Lewis, who introduced the idea in 1923) greatly broadens the definitions of what is an acid and what is a base. Recall that a Lewis acid is an electron pair acceptor and a Lewis base is an electron pair donor. All common organic reactions that do not involve radicals or concerted pericyclic processes can in some manner be discussed as Lewis acid-base reactions. Similarly, all these reactions can be considered to be occurring between electrophiles and nucleophiles. Recall that an electrophile is any species seeking electrons and a nucleophile is any species seeking a nucleus (or positive charge) toward which it can donate its electrons. In this context, a Lewis base is synonymous with a nucleophile, and a Lewis acid is synonymous with an electrophile it just de-... 

This table also demonstrates the equivalence between the two approaches to the modeling of real solutions Lewis approach based on the activity coefficients, and the approach based on the excess values. 

This, procedure for determining the copolymerization parameters is superior to the Mayo-Lewis approach. While the latter requires several experiments, using the above approach, all the information can be obtained from one experiment. 

Lewis s vision lets us see the proton in a different light. The proton itself is the species destined to share the lone pair provided by the base, so it, the proton itself, is the add. This is in marked contrast to the approach 1 explained in Reaction 2, where the acid, such as HCl, is the source of the proton. According to the Lewis approach, the proton, like any other electron-pair acceptor, is the acid. 

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