{"id":3664,"date":"2011-12-22T16:20:18","date_gmt":"2011-12-22T16:20:18","guid":{"rendered":"https:\/\/www.masterorganicchemistry.com\/?p=3664"},"modified":"2026-04-11T11:37:26","modified_gmt":"2026-04-11T16:37:26","slug":"in-summary-resonance","status":"publish","type":"post","link":"https:\/\/www.masterorganicchemistry.com\/2011\/12\/22\/in-summary-resonance\/","title":{"rendered":"In Summary: How To Evaluate Resonance Structures"},"content":{"rendered":"<p><strong>The Four Key Factors In Evaluating Resonance Structures\u00a0<\/strong><\/p>\n<p>Not all resonance forms are of equal importance. So how do we evaluate how &#8220;important&#8221; each resonance structure is?<\/p>\n<p>As we&#8217;ve seen in previous articles, four key factors that determine the importance of resonance structures in organic chemistry are:<\/p>\n<ul>\n<li>Rule #1:<strong> Minimize charges<\/strong><\/li>\n<li>Rule #2: <strong>Full octets are favored<\/strong><\/li>\n<li>Rule #3: How stable are the <strong>negative charges?<\/strong><\/li>\n<li>Rule #4: How stable are the <strong>positive charges?<\/strong><\/li>\n<\/ul>\n<p>Today, let&#8217;s summarize everything we&#8217;ve learned about resonance structures in this unit.<\/p>\n<p><img fetchpriority=\"high\" decoding=\"async\" class=\"alignnone wp-image-37390\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2024\/09\/0-Summary-of-key-concepts-for-Evaluating-Resonance-Structures-full-octets-minimize-charges.gif\" alt=\"Summary of key concepts for Evaluating Resonance Structures - full octets minimize charges\" width=\"640\" height=\"652\" \/><\/a><\/p>\n<p><strong>Table of Contents<\/strong><\/p>\n<ol>\n<li><a href=\"#one\">Recall The Three &#8220;Legal&#8221; Electron-Pushing Arrow &#8220;Moves&#8221; Used For Interconverting Resonance Structures<\/a><\/li>\n<li><a href=\"#two\">Remember That Resonance Structures Are Not In Equilibrium With Each Other &#8211; They Represent Contributions To An Overall Resonance &#8220;Hybrid&#8221;<\/a><\/li>\n<li><a href=\"#three\">Not All Resonance Forms Are Of Equal Significance. So How Do We Evaluate How &#8220;Important&#8221; Each One Is?<\/a><\/li>\n<li><a href=\"#four\">Rule #1: Neutral Resonance Structures Are More &#8220;Important&#8221; Than Charged Resonance Structures<\/a><\/li>\n<li><a href=\"#five\">Rule #2: Full Octets Are Preferable To Empty Octets (And Never, Ever Have Empty Octets On Oxygen or Nitrogen!)<\/a><\/li>\n<li><a href=\"#six\">Rule #3: Place Negative Charges On The Atom Best Able To Stabilize It (i.e. The Least Basic Atom)<\/a><\/li>\n<li><a href=\"#seven\">Rule #4: Place Any Empty Octets On the Atoms Best Able To Stabilize Them (i.e. Carbon And Not Oxygen Or Nitrogen)<\/a><\/li>\n<li><a href=\"#eight\">An Application Of Resonance: &#8220;Pi Donation&#8221;<\/a><\/li>\n<li><a href=\"#nine\">A Second Application Of Resonance: &#8220;Pi Acceptors&#8221;<\/a><\/li>\n<li><a href=\"#notes\">Notes<\/a><\/li>\n<li><a href=\"#quiz\">Quiz Yourself!\u00a0 (On Evaluating Resonance Structures)<\/a><\/li>\n<\/ol>\n<hr \/>\n<h2><a id=\"one\"><\/a>1. Recall The Three &#8220;Legal&#8221; Electron-Pushing Arrow &#8220;Moves&#8221; Used For Interconverting Resonance Structures<\/h2>\n<p>After all these posts about resonance, I thought it would be good to have a post summarizing what&#8217;s been discussed so far.<\/p>\n<p>One of the key skills in analyzing the reactivity of a molecule is to be able to figure out <a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/07\/11\/partial-charges\/\">where the electrons are<\/a>.<\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/11\/15\/how_to_use_electronegativity\/\">\u00a0As I wrote here<\/a>, if we&#8217;re dealing with single bonds, it&#8217;s a relatively straightforward matter of figuring out the differences in electronegativities.<\/p>\n<p>However if multiple bonds (\u03c0 bonds) are present,\u00a0 then we start to run into a little problem:\u00a0 there can be multiple ways to distribute electrons on the same molecule (i.e. different resonance forms).<strong> Therefore, in order to understand electron density on a molecule where pi bonds are present, we must first understand the importance of its various resonance forms.<\/strong><\/p>\n<p>How can we &#8220;find&#8221; resonance forms for a given molecule? It&#8217;s possible to do it through trial-and-error, but one surefire way is to do so is to apply the curved arrow formalism, which is a way of depicting the &#8220;movement&#8221; of electrons.<\/p>\n<p>There are three &#8220;legal&#8221; ways to move electrons using curved arrows: from pi bond to lone pair, from lone pair to pi bond, and from pi bond to pi bond:<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-42680\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/1-summary-of-three-legal-moves-of-resonance-pi-bond-to-lone-pair-lone-pair-to-pi-bond-pi-bond-to-pi-bond.gif\" alt=\"summary of three legal moves of resonance pi bond to lone pair lone pair to pi bond pi bond to pi bond\" width=\"640\" height=\"375\" \/><\/a><\/p>\n<h2><a id=\"two\"><\/a>2. Remember That Resonance Structures Are Not In Equilibrium With Each Other &#8211; They Represent Contributions To An Overall Resonance &#8220;Hybrid&#8221;<\/h2>\n<p>Here&#8217;s an important point about resonance forms. It is tempting (and very wrong!) to think that these\u00a0 resonance forms are in &#8220;equilibrium&#8221; between each other. <strong>Avoid this common mistake!<\/strong><\/p>\n<p>Instead, the &#8220;true&#8221; state of the molecule will be a &#8220;hybrid&#8221; of these resonance forms.<\/p>\n<p>For example in the acetate and allyl cation examples below, the &#8220;true&#8221; structure of the molecule is represented through a 50:50 combination of the two resonance forms.<\/p>\n<p><img decoding=\"async\" class=\"alignnone wp-image-42681\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/2-summary-of-resonance-acetate-ion-resonance-forms-allyl-cation-resonance-hybrid.gif\" alt=\"summary of resonance acetate ion resonance forms allyl cation resonance hybrid\" width=\"640\" height=\"424\" \/><\/a><\/p>\n<h2><a id=\"three\"><\/a>3. Not All Resonance Forms Are Of Equal Significance. So How Do We Evaluate How &#8220;Important&#8221; Each One Is?<\/h2>\n<p>In the case of the acetate ion and the allyl cation,\u00a0 both resonance forms are equal in energy, so the &#8220;hybrid&#8221; is a 1:1 mixture of the two. However, this is only rarely the case.<\/p>\n<p>Take the ketone below (acetone, or &#8220;propanone&#8221;) for which we can draw 3 different resonance forms.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-42682\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/3-resonance-forms-of-acetone-unequal-resonance-forms.gif\" alt=\"resonance forms of acetone unequal resonance forms\" width=\"640\" height=\"241\" \/><\/a><\/p>\n<p>In cases like these, how do we evaluate the relative importance of each resonance form?<\/p>\n<h2><a id=\"four\"><\/a>4. Rule #1: Neutral Resonance Structures Are More &#8220;Important&#8221; Than Charged Resonance Structures<\/h2>\n<p>Resonance forms become <strong>less significant<\/strong> as the number of charges are increased (<a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/08\/evaluating-resonance-forms-1-the-rule-of-least-charges\/\">see earlier post<\/a>).<\/p>\n<p>For example, in the ketone above, the resonance form with <strong>zero formal charges<\/strong> will be the most significant.<\/p>\n<p>How do we know? We can measure the physical properties of the molecule (e.g. boiling points, solvent properties, conductivity) and see if it&#8217;s more consistent with a charged species or a neutral compound.<\/p>\n<p>All the physical properties of propanone (acetone) are consistent with it being a (mostly) neutral molecule. For example acetone has a boiling point of 56\u00b0C, significantly lower than water, and a freezing point of \u201395\u00b0C. It doesn&#8217;t dissolve charged species (like NaCl) nearly as well as water does. And it isn&#8217;t a particularly good conductor of electricity.<\/p>\n<p>That isn&#8217;t to say that the &#8220;second-best&#8221; resonance form doesn&#8217;t play <em>some<\/em> role.<\/p>\n<p>Acetone is much higher-boiling than butane (\u20131\u00b0C) which has a similar molecular weight due to the dipole-dipole Van der Waals attractive forces, and as we&#8217;ll see later, the &#8220;second-best&#8221; resonance form can yield an important clue as to the reactivity of a molecule.<\/p>\n<h2><a id=\"five\"><\/a>5. Rule #2: Full Octets Are Preferable To Empty Octets (And Never, Ever Have Empty Octets On Oxygen or Nitrogen!)<\/h2>\n<p>Resonance forms where all atoms have full octets will be more significant than resonance forms where atom(s) lack a full octet. Importantly, it&#8217;s a <a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/12\/evaluating-resonance-structures-2-applying-electronegativity\/\">good general rule<\/a> <strong>never to place less than a full octet on nitrogen or oxygen<\/strong>, as in the acetone example (above right). Since these atoms are highly electronegative, these resonance forms are extremely unstable and will be insignificant.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-42683\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/4-resonance-form-evaluation-best-to-give-atoms-full-octets.gif\" alt=\"resonance form evaluation best to give atoms full octets\" width=\"640\" height=\"237\" \/><\/a><\/p>\n<h2><a id=\"six\"><\/a>6. Rule #3: Place Negative Charges On The Atom Best Able To Stabilize It (i.e. The Least Basic Atom)<\/h2>\n<p>Given that neutral resonance structures are preferred overall, when a resonance structure absolutely must bear a negative charge somewhere, <a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/13\/evaluating-resonance-forms-3-where-to-put-the-negative-charge\/\">place it on the atom best able to stabilize that charge.<\/a> Since, in essence,\u00a0 &#8220;basicity is the opposite of stability&#8221;, this is the same as saying, &#8220;put the negative charge on the least basic atom&#8221;.<\/p>\n<p>The good news here is that if you understand the factors that affect acidity, you also understand the factors which stabilize negative charge.<\/p>\n<p>There are four main trends to consider here:<\/p>\n<ul>\n<li><strong>Electronegativity<\/strong>: across a row of the periodic table, negative charge becomes more stable as electronegativity is increased.<\/li>\n<li><strong>Polarizability:<\/strong> down a column of the periodic table, negative charge becomes more stable as polarizability increases<\/li>\n<li>Electron withdrawing groups stabilize negative charge through <strong>inductive effects<\/strong>.<\/li>\n<li><strong>Hybridization<\/strong>: negative charge becomes more stable as the s-character of the atom is increased.\u00a0 sp (most stable) &gt; sp<sup>2<\/sup> &gt; sp<sup>3<\/sup> (least stable<\/li>\n<\/ul>\n<p>Note again that <em>stability is the opposite of basicity<\/em>.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-42684\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/5-stability-of-negative-charge-summary-for-evaluating-resonance-forms.gif\" alt=\"stability of negative charge summary for evaluating resonance forms\" width=\"640\" height=\"552\" \/><\/a><\/p>\n<h2><a id=\"seven\"><\/a>7. Rule #4: Place Any Empty Octets On the Atoms Best Able To Stabilize Them (i.e. Carbon And Not Oxygen Or Nitrogen)<\/h2>\n<p>As we said above, full octets are best. However, when dealing with a resonance structure where there absolutely must be an atom with less than a full octet, then <a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/14\/evaluating-resonance-forms-4-positive-charges\/\">follow these principles<\/a>:<\/p>\n<ol>\n<li>Place the empty octet on <strong>carbon<\/strong>, never oxygen or nitrogen<\/li>\n<li>Place place the empty octet on the <strong>most substituted carbon\u00a0<\/strong>(remember <a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/03\/11\/3-factors-that-stabilize-carbocations\/\">carbocation stability<\/a>)<\/li>\n<li><strong>Avoid<\/strong> placing positive charge adjacent to electron withdrawing groups if possible<\/li>\n<li>Place positive charge preferentially on <strong>alkyl<\/strong> carbocations as opposed to\u00a0<strong>alkenyl\u00a0<\/strong>or (especially)\u00a0<strong>alkynyl\u00a0<\/strong>carbons.<\/li>\n<\/ol>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-42685\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/6-carbocation-stability-resonance-forms-increase-in-stability-with-substitution-decrease-with-adjacent-ewgs.gif\" alt=\"carbocation stability resonance forms increase in stability with substitution decrease with adjacent ewgs\" width=\"640\" height=\"589\" \/><\/a><\/p>\n<h2><a id=\"eight\"><\/a>8. An Application Of Resonance: &#8220;Pi Donation&#8221;<\/h2>\n<p>When double bonds are connected to an atom with a lone pair of electrons, the molecule will have a significant resonance form where there is <strong>negative charge on the adjacent carbon\u00a0<\/strong>due to a phenomenon called, &#8220;<a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/15\/exploring-resonance-pi-donation\/\">pi donation<\/a>&#8220;. This becomes particularly important once you start learning about reactions of pi bonds.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-42686\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/7-summary-of-pi-donation-when-pi-donating-substituents-adjacent-to-c-c-pi-bond-resonance-hybrid-has-partial-negative-charge.gif\" alt=\"summary of pi donation when pi donating substituents adjacent to c c pi bond resonance hybrid has partial negative charge\" width=\"640\" height=\"315\" \/><\/a><\/p>\n<h2><strong><a id=\"nine\"><\/a>9. A Second Application Of Resonance: &#8220;Pi Acceptors&#8221;<\/strong><\/h2>\n<p>When double bonds are connected to a polarized \u03c0 bond, the molecule will have a significant resonance form where there is positive charge on the adjacent carbon. This phenomenon is known as &#8220;pi-accepting&#8221; behavior, and these groups are known as &#8220;<a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/19\/exploring-resonance-pi-acceptors\/\">pi acceptors<\/a>&#8220;.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-42687\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/2019\/11\/8-pi-acceptors-partial-positive-charge-on-alkene-conjugaed-with-electron-withdrawing-group.gif\" alt=\"pi acceptors partial positive charge on alkene conjugaed with electron withdrawing group\" width=\"639\" height=\"286\" \/><\/a><\/p>\n<p>For now, that does it for a summary of the important themes in resonance. Next stop (after a post about some common mistakes) will be to apply these principles to chemical reactivity.<\/p>\n<p><strong>Next Post: <\/strong><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/01\/10\/common-mistakes-how-not-to-draw-resonance-curved-arrows\/\">Common Mistakes &#8211; How NOT to Draw Resonance Curved Arrows<\/a><\/p>\n<hr \/>\n<h2><a id=\"notes\"><\/a>Notes<\/h2>\n<div class=\"related-articles\"><p><strong>Related Articles<\/strong><\/p><ul><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/01\/10\/common-mistakes-how-not-to-draw-resonance-curved-arrows\/\" class=\"\"><span>Drawing Resonance Structures: 3 Common Mistakes To Avoid<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/13\/evaluating-resonance-forms-3-where-to-put-the-negative-charge\/\" class=\"\"><span>Evaluating Resonance Structures With Negative Charges<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/14\/evaluating-resonance-forms-4-positive-charges\/\" class=\"\"><span>Evaluating Resonance Structures With Positive Charge<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/12\/evaluating-resonance-structures-2-applying-electronegativity\/\" class=\"\"><span>How To Find The Best Resonance Structure By Applying Electronegativity<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/11\/30\/introduction-to-resonance-2-curved-arrows\/\" class=\"\"><span>How To Use Curved Arrows To Interchange Resonance Forms<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/12\/15\/exploring-resonance-pi-donation\/\" class=\"\"><span>Exploring Resonance:  Pi-Donation<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2011\/03\/11\/3-factors-that-stabilize-carbocations\/\" class=\"\"><span>3 Factors That Stabilize Carbocations<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/2012\/02\/27\/7-factors-that-stabilize-negative-charge-in-organic-chemistry\/\" class=\"\"><span>7 Factors that stabilize negative charge in organic chemistry<\/span><\/a><\/li><li><a href=\"https:\/\/www.masterorganicchemistry.com\/organic-chemistry-practice-problems\/resonance-structures-practice\/\" class=\"\"><span>Resonance Structures Practice (MOC Membership)<\/span><\/a><\/li><\/ul><\/div>\n<h2><a id=\"quiz\"><\/a>Quiz Yourself on Resonance Structures<\/h2>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0005-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0006-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0007-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0008-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0009-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/0010-Front-Image-Only.png\" alt=\"\" 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a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/3678-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n\n<p class=\"p1\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-26714\" src=\"https:\/\/www.masterorganicchemistry.com\/wp-content\/uploads\/quiz-previews\/3679-Front-Image-Only.png\" alt=\"\" width=\"640\" height=\"616\" \/><\/p>\n<p><a href=\"https:\/\/www.masterorganicchemistry.com\/moc-membership\/\"><strong>Become a\u00a0 MOC member<\/strong><\/a> to see the clickable quiz with answers on the back. <\/p>\n","protected":false},"excerpt":{"rendered":"<p>The Four Key Factors In Evaluating Resonance Structures\u00a0 Not all resonance forms are of equal importance. So how do we evaluate how &#8220;important&#8221; each resonance <\/p>\n","protected":false},"author":1,"featured_media":37390,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1406],"tags":[173,391,334,390,389,392,305,388,267],"post_folder":[],"class_list":["post-3664","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bonding-structure-resonance","tag-arrow-pushing","tag-charge-stabilization","tag-electron-density","tag-least-charges","tag-negative-charge","tag-pi-acceptors","tag-pi-donation","tag-positive-charge","tag-resonance"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Resonance Structures: 4 Rules On How To Evaluate Them, With Practice<\/title>\n<meta name=\"description\" content=\"Four key factors to help you evaluate resonance 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