Chemistry by Saloni singh on Instagram: "Resonance Effect Order (Strongest → Weakest) Positive Resonance (+R or +M) Group Order (Electron Donating / Ring Activating) −O − >−NH 2 ​ >−NHR>−NR 2 ​ >−OH>−OR>−NHCOCH 3 ​ >−OCOR>−Ph>−F>−Cl>−Br>−I Key Points to Note: −O − is strongest due to full negative charge. Nitrogen groups (−NH 2 ​ , −NR 2 ​ ) are generally stronger than Oxygen groups (−OH, −OR) because Nitrogen is less electronegative and can donate its lone pair more easily. Amides (−NHCOCH 3 ​