An alternative procedure to writing Lewis structures

Abstract

Writing Lewis StructuresNo present day textbook of organic chemistry disregards the resonance structures. They are taken from the valence bond method and are relatively easy, involving little mathematics. The structures are applied to ir-electron systems and their purpose is to determine the charge distribution and centers of reactivity and also the energetically favored isomers.Beginners often find it difficult to write down all the structures (1) and to apply correctly the concept that the actual state (resonance hybrid) is a mixture of all contributing resonance structures (canonical forms) with different influence. Handling bigger molecules involves much expenditure of time for those without much experience. Under these circumstances it is useful to consider the method using simple MO pictures. In this article the method will be explained using simple examples. It is relatively well known, is mentioned in many monographs (2), is applied almost only to carbon compounds (3), and is hardly mentioned in the elementary textbooks although its simplicity and efficiency would justify it. The method utilizes the results of the Hiickel calculation. The simpleness of the method comes from the fact that some results can be obtained without the solution of the secular determinant.It is necessary to know the basic geometry of the molecule. This cannot be obtained from the valence bond nor the molecular orbital method. The atomic models of Gillespie are applied here (4).Before one goes deeper into the methods, several remarks concerning resonance structures are mentioned. (1) Molecules exist whose atoms carry partial charges, although all the atoms are equal and possess the same electronegativity. An explanation is obtained by drawing resonance structures, e.g., ozone

Facile Method for Constructing Lewis (Electron Dot) Structures

“…Lewis electron dot structures are critical to our rationalization of the structures and chemistry of the p-block elements. The early work by Lewis, Pauling, and others in this area is fundamental to our modern understanding of chemistry. , However, as stated by Lever in 1972: “Until expertise has been gained, confusion often arises concerning the correct number of multiple bonds to use, the correct number of valence electrons to use, and the placing of formal charges.” Since then, there has been a lot of research and discussion into the difficulties of drawing Lewis structures − as well as the development of a variety of procedures, or modifications to existing procedures. ,,− Kaufmann et al recently found that “it is possible to distinguish three main components to these procedures. At first, there is an initial element of construction: construct a Lewis structure by calculating the total number of valence electrons, draw the skeletal structure and distribute the remaining electrons.” Distribution of the remaining electrons is then done such that the octet rule is satisfied for each atom (except for H which normally has only two electrons).…”

Connecting the Dots: Lewis Structure Builder Web App as a Review Tool for Organic Chemistry

“…Over time, several authors have devised methods to teach Lewis structures in a systematic manner, and some computer applications that can be used to practice the skill of drawing Lewis structures have been reported. ,,− These vary from plug-ins that can be added to existing drawing programs to complex web-based tools and freehand drawing applications. Some of the available methods highly limit the choices that students can make or require that students learn a set of rules in order to access the information creating what Cooper et al describe as a non-naturalistic interface .…”

History and Future of Dative Bonds

“…They evidently cannote xplain or match all the properties of all the molecules, but they provideamuch better representation of many Lewiss tructure "failures". Since there is nothingn ew under the sun, we must point out that we base our notation in the works of many others that realized that something was missingf rom the classical Lewis structures, [7][8][9][10][11][12] especially the Linnett double-quartet [13,14] andt he Green-Green-Parkin halfarrow. [15] We expressly avoided complex bond-dissection computational methodologies [16] to keep the article as simple as possible for all the chemistry public, and we even kept the number of orbitals to am inimum.…”

“…They evidently cannot explain or match all the properties of all the molecules, but they provide a much better representation of many Lewis structure “failures”. Since there is nothing new under the sun, we must point out that we base our notation in the works of many others that realized that something was missing from the classical Lewis structures, especially the Linnett double‐quartet and the Green‐Green‐Parkin half‐arrow …”