What is the fundamental difference between Tautomerism and Resonance? — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Tautomerism involves the actual physical breaking and forming of sigma bonds and the movement of atomic nuclei, creating a real, separable equilibrium. Resonance is a hypothetical concept involving only the delocalization of $\pi$-electrons and lone pairs; atomic nuclei never move.