Personal opinion: electronic effect is based on the size of electronegativity between atoms or groups to distinguish, the effect of large electronegativity on small groups is to attract electrons, and in turn is to push electrons. Conjugation is that there are double bonds, triple bonds, benzene rings and other electrons can be active on the gas structure, there are π-π conjugation, p-π conjugation, σ-π hyperconjugation, push and suction are mainly determined by electronegativity. Electronegativity of common elements: Hydrogen 2.1 Lithium 1.0 Beryllium 1.57 boron 2.04 carbon 2.55 nitrogen 3.04 oxygen 3.44 Fluorine 4.0 sodium 0.93 magnesium 1.31 aluminum 1.61 silicon 1.90 phosphorus 2.19 sulfur 2.58 Chlorine 3.16 bromine 2.96 iodine 2.66 halogen atoms have large electronegativity and are strong electron absorbing groups. Because halogen atoms do not share electron pairs to form p-pi conjugation with benzene ring, the electron giving effect is not enough to offset the influence caused by the induction effect of electron absorbing, so the overall result is to passivate the benzene ring. One thing to remember about halogenated benzene is that the vividness is controlled by a strong inducible effect, and the bilocational effect is controlled by a conjugation effect. The question of why halogenated benzene is a para-substitution can be explained by resonance theory: there are two transition states between the addition of halogenated benzene to electrophiles and the final product: Pi-sigma-complex, the conversion between the two is the decisive step of the reaction. For the electron pushing group EDG, the carbocation intermediate composed of the meta-substitution has the worst stability, so the activation energy is the highest and the reaction is the slowest. For the electron-withdrawing group EWG, the carbocation intermediates composed of meta-substitution have the highest stability, so the activation energy is the lowest and the response is the fastest. These resonance diagrams can be drawn by themselves and understood at a glance. Overall for halogens: the relative increase in the density of the carbon atoms on the adjacent parposition, although the overall electron cloud density decreases. I don't know how you get the odds in this picture that you provide, but if you want to calculate them theoretically, I don't think it's possible. You can read some books on structural chemistry, and there are lots of theories (mostly quantum ones) on how to calculate the charge density of the other carbon atoms in the benzene ring after a halogen atom is added. I think the probability data you provide should be based on the ratio of the product after the addition of raw materials. Personally, I think it is only necessary to analyze why the probability of electrophilic addition of neighboring para-carbon atoms is different. Horizontal comparison: the substitution probability of F to I is getting higher and higher, because from F to I, the electron cloud density on the benzene ring is gradually increased due to the conjugation effect, which is conducive to electrophilic substitution; Vertical comparison: that is, the substitution probability on the adjacent para-carbon atom is the highest and the smallest. As for the parapet, the probability is lower than parapet because of the steric hindrance effect of the proximity of the parapet carbon atom to the halogen atom. As for why the counterpoint is affected by the conjugation effect, as mentioned earlier: the conjugation effect determines the orientation of the addition, while the induction effect determines the difficulty of the addition, because the induction effect determines the density of the electron cloud on the benzene ring. From the graph, you can also see that the probability of adding parappositions between F and I, especially the probability of parappositions, is becoming more and more the same, which is due to the effect of conjugation of halogen atoms.