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The Chemical Educator

ISSN: 1430-4171 (electronic version)

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Abstract Volume 7 Issue 5 (2002) pp 249-257

Toward a Dynamic Lewis Notation

Roy W. Clark

Department of Chemistry, Middle Tennessee State University, Murfreesboro, TN 37132
Received March 18, 2002. Accepted May 28, 2002

Published online: 20 September 2002

Abstract. Because the presently used Lewis diagrams have their roots in static electron theories of the early twentieth century, this paper proposes substituting a double-arrow symbolism for the customary double dots. This means that students should be taught that a bond line (or “stick” as some call it) means a double arrow, not a double dot. Lone pairs are to be represented by double-curved arrows and later abbreviated to the old familiar double dot. There are obvious advantages to this new notation when atoms have different electronegativities. The double arrows can suggest the shifting of the bond pair equilibrium toward the most electronegative atom. The new notation is more compatible with VSEPR theory, and it seems to suggest the loci of largely imaginary MOs and AOs by the configuration of the arrows. With the help of some imagination, the new symbolism can clarify resonance in aromatic molecules and conjugated chains. The most radical suggestion is that resonance forms be abandoned in favor of conjugated blur bonds. The concept of blur bonds has the merit of being easily extendable to the explanation of metal bonding and electron conduction.

Key Words:  In the Classroom; organic chemistry; NMR; computers

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Issue date: October 1, 2002

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