11 Chap 3 | Chemical Bonding 07 | VSEPR theory | TrigonalBipyramidal Octahedral | Shape Geometry etc

AB₅ and AB₆ Types: Trigonal Bipyramidal and Octahedral Geometry (VSEPR Theory) | Class 11 Chemistry

In this lecture, we study the AB₅ and AB₆ types of molecules and ions using VSEPR Theory, with special emphasis on their molecular geometry and hybridization.

For AB₅ type molecules, the electron pair arrangement leads to a trigonal bipyramidal geometry. In this geometry, the central atom forms five bonds arranged in two different positions: three equatorial bonds and two axial bonds. The corresponding hybridization is sp³d. Examples include PCl₅ and the triiodide ion (I₃⁻), which exhibit trigonal bipyramidal electron geometry.

AB₅ type species, five regions of electron density around the central atom lead to a trigonal bipyramidal electron geometry. In this arrangement, three bonds occupy equatorial positions and two occupy axial positions to minimize electron pair repulsion. The central atom undergoes sp³d hybridization. Important examples of AB₅ type species include PCl₅, XeF₂O₃, and XeF₂, where the electron pairs are arranged in a trigonal bipyramidal geometry.

For AB₆ type molecules, six bonding pairs around the central atom result in an octahedral geometry, where all bond angles are 90°. The central atom undergoes sp³d² hybridization to accommodate six equivalent bonds. A classic example is XeF₆, which shows octahedral electron geometry due to the involvement of expanded valence shell orbitals.
AB₆ type species, six bonding pairs around the central atom result in an octahedral geometry, in which all bond angles are 90°. The corresponding hybridization is sp³d². A common example is XeF₄ , which follows an octahedral electron pair arrangement according to VSEPR theory.

This lecture helps students understand how hybridization corresponds to molecular geometry in higher coordination compounds, an important concept in chemical bonding and molecular structure for Class 11 Chemistry.
Links of Lectures
11 Chap 3 | Chemical Bonding 05 | VSEPR theory | Shapes of Molecules | Geometry , Hybridisation ,etc
   • 11 Chap 3 | Chemical Bonding 05 | VSEPR th...  
11 Chap 3 | Chemical Bonding 06 | VSEPR theory | AB2 , AB3, AB4 | Shape Geometry , Hybridisation etc
   • 11 Chap 3 | Chemical Bonding 06 | VSEPR th...