Lewis Structures in General Chemistry: Agreement between Electron Density Calculations and Lewis Structures

• Autores: Gordon H. Purser
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 78, Nº 7, 2001, pág. 981
• Idioma: inglés
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• Resumen

  • How to draw the most appropriate Lewis structure for molecules and ions in which nonmetal atoms beyond the second period are bonded to a terminal oxygen atom has been the subject of considerable debate. Recently there has been a shift toward satisfying the octet rule even if formal charges remain on the structure. In this work, the internuclear electron densities of a series of X-O bonds (where X = P, S, or Cl) have been calculated using quantum mechanics and compared to Lewis structures for which the formal charges have been minimized. A direct relationship was found between the internuclear electron density and the bond order predicted from Lewis structures in which formal charges are minimized. This relationship suggests that obeying the octet rule at the expense of having formal charges does not yield the most appropriate Lewis structure. Instructors are urged to teach students to minimize formal charges where possible.