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

摘要

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 soft-ware 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.