Systematic Procedure for Drawing Lewis Structures Based on Electron Pairing Priority and the Explicit Use of Donor Bonds: An Alternative to the Normal Procedure Which Can Be Pen and Paper Based or Automated on a PC in User Interactive 3D

Abstract

This article contrasts the normal method for drawing Lewis structures with a two-step systematic approach. The latter approach uses a known molecular connectivity and a knowledge of the number of valence electrons that each atom possesses to visualize bonds that are formed by pairing electrons, one from each atom. This process is repeated until at least one of the non-hydrogen atoms in each bond has an octet. Donor bonds are added when atoms with six and eight electrons are adjacent. In forming donor bonds charges are added to the atoms involved to maintain electron accounting and there is no need to use a formula to calculate formal charges. The general importance of adhering to the octet rule for p-block compounds is stressed and the difference between covalent and donor bonds and the use of the recent IUPAC definition of oxidation state which is based on Lewis structures is included in the discussion. When students are able to draw Lewis structures they can be given access to PC software, available on an academic free basis, which will draw rotatable Lewis structures in 3D for p-block compounds. The software allows the user to move electron pairs in a bow and arrow fashion within the structures and atoms are highlighted when the octet is exceeded.

Addressing the Hypervalent Model: A Straightforward Explanation of Traditionally Hypervalent Molecules

“…It should be stressed that the computational evidence is not intended as a teaching tool in a regular general chemistry course but is the basis for revising the models we use to teach. Similar attempts in the near past show the importance of this topic …”

Facile Method for Constructing Lewis (Electron Dot) Structures

“…Some of the advantages compared to the stepwise pairing processes that similarly do not require a total valence electron count − are that Individual electrons do not need to be drawn and individually paired up; Formal charges are easily and automatically generated; It is not necessary to decide where to put an extra electron in the case of a negative charge (or remove in the case of a positive charge). …”

“…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).…”

“…As already noted by Kaufmann, most procedures require a total valence electron count; however, a couple rely on a stepwise pairing process of valence electrons. − The procedure I will describe here does not require a total valence electron count, the drawing and pairing-up of individual electrons, or modification steps involving rearrangements of lone pairs (rearrangements of bonding pairs, however, readily provide a variety of valid Lewis structures). Furthermore, my procedure does not need a formal charge formula, or even the drawing of the lone pairs.…”

Dealing with Lewis structures in chemistry lessons

“…The general challenges in creating Lewis structures remain with this model (McArdle, 2019). Large structures, such as those required in carbohydrate chemistry, can only be displayed with considerable effort.…”