Resonance Hybrids_CHEM 236_Spring 20100

Resonance Hybrids_CHEM 236_Spring 20100 - headed arrow...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
CHEMISTRY 236 ORGANIC CHEMISTRY Resonance Hybrids Molecules which are not adequately represented by a single Lewis structure are often described as a hybrid of two or more Lewis structures. A resonance hybrid has only a single stable structure . However, representation of a compound by two or more structures gives a more accurate description of its properties than does the single representation. Resonance hybrids often have greater stability than either of the contributing structures would suggest and are said to have resonance energy and to be “stabilized by resonance.” Representing Resonance Hybrids Structures which are used to represent resonance hybrids can be called resonance structures or contributing structures. Contributing structures are different correct representations of a molecular structure which have identical atomic positions , the same number of paired electrons and conform to the conventional rules of valence and charge. The contributing structures are connected by a special double-
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: headed arrow which is used only for this representation. The structures drawn are fictional, limiting structures which are contributors to the single stable structure of the hybrid molecule. IN DRAWING RESONANCE HYBRIDS, THE FOLLOWING RULES ARE FOLLOWED: (1) The atomic positions are identical in all contributing structures. The contributing structures must fulfill the rules of valence and charge as dictated by the Periodic Table. (2) All structures must have the same pairing of electron spins and be formally interconverted by redistributions of electrons. (3) Charge structures should be in accord with the ability of the atom to bear charge. Opposite charges are most favorable when close together in a structure and like charges are most favorably separated. (4) Curves with two-sided arrowheads are used to show the difference in two electron formal bonding for structures which have the same atomic positions....
View Full Document

This note was uploaded on 12/30/2011 for the course CHEM 236 taught by Professor Baranger during the Spring '08 term at University of Illinois at Urbana–Champaign.

Ask a homework question - tutors are online