240 likes | 620 Views
Theories of Covalent Bonding. Valence Bond (VB) Theory and Orbital Hybridization. The Mode of Orbital Overlap and the Types of Covalent Bonds. The Central Themes of VB Theory. Basic Principle.
E N D
Theories of Covalent Bonding Valence Bond (VB) Theory and Orbital Hybridization The Mode of Orbital Overlap and the Types of Covalent Bonds
The Central Themes of VB Theory Basic Principle A covalent bond forms when the orbitals of two atoms overlap and the overlap region, which is between the nuclei, is occupied by a pair of electrons. The two wave functions are in phase so the amplitude increases between the nuclei.
The Central Themes of VB Theory Themes A set of overlapping orbitals has a maximum of two electrons that must have opposite spins. The greater the orbital overlap, the stronger (more stable) the bond. The valence atomic orbitals in a molecule are different from those in isolated atoms. There is a hybridization of atomic orbitals to form molecular orbitals.
Orbital overlap and spin pairing in three diatomic molecules. Hydrogen, H2 Hydrogen fluoride, HF Fluorine, F2
Key Points Types of Hybrid Orbitals sp sp2 sp3 sp3d sp3d2 Hybrid Orbitals The number of hybrid orbitals obtained equals the number of atomic orbitals mixed. The type of hybrid orbitals obtained varies with the types of atomic orbitals mixed.
The sp hybrid orbitals in gaseous BeCl2. atomic orbitals hybrid orbitals orbital box diagrams
The sp hybrid orbitals in gaseous BeCl2. orbital box diagrams with orbital contours
both C are sp3 hybridized s-sp3 overlaps to s bonds sp3-sp3 overlap to form a s bond relatively even distribution of electron density over all s bonds The s bonds in ethane(C2H6).