The relationship between hybrid orbital theory and the theory of mutual exclusion of valence layer electron pairs

1) Explain the molecular geometry

Both hybrid orbital theory and valence electron pair mutual exclusion theory can explain the geometric configuration of molecules
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For example, to explain the tetrahedral configuration of CH ₄ , according to the hybrid orbital theory, C adopts sp ³ equivalent hybridization, and the four hybrid orbitals are distributed in tetrahedron so that CH ₄ has a tetrahedral configuration; according to the valence electron pair According to the theory of mutual exclusion, there are 4 electron pairs in the C valence layer, and the valence layer electron pairs are distributed in a tetrahedron.

Valence layer electron pair mutual exclusion theory judges the geometric configuration of molecules by the number of electron pairs and the configuration of electron pairs, while hybrid orbital theory explains the geometric configuration of molecules and explains the formation process of this configuration
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2) Correspondence between orbital hybridization type and electron pair configuration

The number of electron pairs in the central valence layer generally corresponds to the hybridization type of the orbital, that is, the configuration of the electron pair corresponds to the hybridization type of the orbital
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The valence layer electron pair or the electron pair configuration of the central atom can be judged first from the valence layer electron pair mutual exclusion theory, and then the hybridization type of the central atom can be judged, such as 2 pairs of electrons, linear shape, sp hybridization; 3 pairs of electrons, Equilateral triangle, sp ² hybrid; 4 pairs of electrons, regular tetrahedron, sp ³ hybrid; 5 pairs of electrons, triangular double cone, sp ³ d hybrid; 6 pairs of electrons, regular octahedron, sp ³ d ² hybrid

The exception is that CIO ₂ has 4 pairs of electrons, but Cl adopts sp ² hybridization instead of sp ³ hybridization (not discussed in detail here)
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3) The relationship between solitary electron pair and hybridization type

If the number of ligands is equal to the number of pairs of electrons in the valence layer and there is no lone electron pair in the molecule, the central atom adopts equal hybridization, such as BCl ₃ , SO ₃ and PF ₅ molecules; if the number of ligands is less than the number of pairs of electrons in the valence layer, If there is a lone electron pair in the molecule, the central atom adopts unequal hybridization, such as H ₂ O, NH ₃ and SF ₄ molecules
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If it is equal hybridization, the hybrid orbital distribution is consistent with the molecular configuration; if it is unequal hybridization, the lone electron pair occupies the hybrid orbit but not as a vertex.
After determining the position of the lone electron pair, the rest of the hybrid orbital and When the ligand forms a bond, the structure of the molecule can be determined
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The valence layer orbital electrons that are not involved in the hybridization generally form a π bond or a delocalized π bond