All Chapters Video 1.5 Resonance Structures Chapter OutlineChapter Quiz Question? Ask Dr. Mike! Lesson Summary Definition There are some molecules that have pi electrons that can move around from one atom to another. For example, the following molecules (A and B) are both different forms of acetate: Structures A and B are called resonance structures (or resonance contributors). In reality, acetate actually exists somewhere in-between A and B, with the – charge being shared equally by the two oxygens. Resonance Rules When drawing different resonance structures, remember: 1. Only electrons move. Specifically, only pi electrons, lone-pair electrons, or negative charges can move. Do NOT move atoms.2. You CAN move electrons toward or into an atom that does NOT have a full octet, such as carbocations.3. If an atom already HAS a full octet, then you can move electrons into it ONLY IF you push electrons out the opposite side (electrons in, electrons out).4. Do not move or break sigma bonds, only pi bonds. Determining Greatest Resonance Contributor 1. The most stable resonance structure will have a full octet on every atom.2. The most stable resonance structure will have the smallest possible number of charges.3. The most stable resonance structure will have negative charges on the most electronegative atoms and positive charges on the least electronegative atoms. Lesson 1.5 Resonance Structures 1.0 Meet Dr. Mike Christiansen! 1.1 Molecular Bonding Geometry and Hybridization 1.1 Quiz Video Solution 1.2 Condensed Formulas and Line-Bond Formulas 1.2 Quiz Video Solution 1.3 Sigma and Pi Bonds 1.3 Quiz Video Solution 1.4 Orbital Hybridization 1.4 Quiz Video Solution 1.5 Resonance Structures 1.5 Quiz Video Solution 1.6 Newman Projections 1.6 Quiz Video Solution 1.7 Cycloalkanes and Ring Strain 1.7 Quiz Video Solution Instructor Dr. Mike Christiansen Dr. Christiansen is a chemistry professor at Utah State University and has a PhD in organic chemistry. He's been teaching students chemistry for nearly 12 years.