The Mesomeric effect is the effect of the overlap of a p-orbital with the p-orbital on an adjacent atom in the chemical compound to form a delocalised cloud of electrons over both the atoms called a π (pi) bond. P-orbitals on many atoms may all overlap, to form an extensive π bond but only as long as the number of electrons on each atom in the conjugated system does not exceed the maximum allowed and the chain of atoms is continuous. The effect is symbolized by M. The mesomeric effect of delocalised electrons occurs in unsaturated organic compounds, where the double bond is separated by a single bond. Examples butadi-1,3-ene and aromatic compounds. óéàThe discussion below presumes knowledge of material contained at Atomic orbital. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (Ï€ bonds) are bonds with a single nodal plane containing the line segment between the two atoms. ... A chemically conjugated system, is a system of atoms covalently bonded with alternating single and double bonds (e. ... In chemistry, delocalized electrons are electrons in a molecule that do not belong to a single atom or a covalent bond. ... An organic compound is any of a large class of chemical compounds whose molecules contain carbon, with exception of carbides, carbonates and carbon oxides. ...

The effect is responsible for stability greater than that predicted. It affects the stability of compounds by resonating the electrons/charge over the molecule. Thus it can stabilise the anion formed after the loss of a proton, making the compound more acidic. Additionally, the effect of delocalising the electrons and therefore the charge, will reduce the probability of the anion being reprotonated as it is now a "soft nucleophile" (disperse charge) compared to the "hard electrophile" of the proton (small localised charge). Resonance structures of Benzene Resonance structures are diagrammatic tools used predominately in organic chemistry to symbolize resonant bonds between atoms in molecules. ... For alternative meanings see acid (disambiguation). ... An anion is an ion with negative charge. ... In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ...

It's important to note that the mesomeric affect as a result of p - orbital overlap has absolutely no affect on the inductive effect, as this effect is purely to do with the electronegativity of the atoms and their structural chemistry (which atoms are connected to which). The inductive effect is associated with the dipole moment of the compound R-X. If X is at the negative end of a dipole moment, it will draw electrons from the ring and produce -I effect. ... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ...