Hybridization PDF

Outlines Valence Bond (VB) Theory and Orbital Hybridization. HYBRIDIZATION The Mode of Orbital Overlap and the Types of Covalent...

Outlines Valence Bond (VB) Theory and Orbital Hybridization. HYBRIDIZATION The Mode of Orbital Overlap and the Types of Covalent Bonds. Molecular Orbital (MO) Theory and Electron Delocalization. DR AMALINA MOHD TAJUDDIN 1 2 Hybridization – mixing of two or more atomic orbitals to form a new set of hybrid orbitals. sp The number of hybrid orbitals obtained equals the number of atomic orbitals mixed. The type of hybrid orbitals obtained varies with the types of sp³d² sp² atomic orbitals mixed. Types of Hybrid Orbitals Types of Hybrid Orbitals sp sp2 sp3 sp3d sp3d2 sp³d sp³ 4 3 4 1  How do I predict the hybridization of the central atom? Sigma (s) bond is formed by sideway overlapping of two atomic orbitals Count the number of lone pairs AND the number electron density is concentrated along the internuclear axis of atoms bonded to the central atom # of Lone Pairs + # of Bonded Atoms Hybridization Examples 2 sp BeCl2 3 sp2 BF3 4 sp3 CH4, NH3, H2O 5 sp3d PCl5 6 sp3d2 SF6 5 6 The sp hybrid orbitals in gaseous BeCl2. The sp hybrid orbitals in gaseous BeCl2 atomic orbitals hybrid orbitals orbital box diagrams with orbital contours orbital box diagrams 7 8 2  The sp2 hybrid orbitals in BF3 The sp3 hybrid orbitals in CH4 Animation sp3 9 10 The sp3 hybrid orbitals in NH3 The sp3 hybrid orbitals in H2O 11 12 3  The sp3d hybrid orbitals in PCl5 The sp3d2 hybrid orbitals in SF6 13 14 A single bond is a sigma bond 15 16 4 The p-bond in ethylene. The shape of the molecule has something to do with the orbitals of carbon. Pi bond (p) – electron density above and below plane of nuclei of the bonding atoms Sigma bond (s) – electron density is concentrated around the inter nuclear axis 17 18 19 20 5  Sigma (s) and Pi Bonds (p) Single bond 1 sigma bond Double bond 1 sigma bond and 1 pi bond Triple bond 1 sigma bond and 2 pi bonds How many s and p bonds are in the acetic acid (vinegar) molecule CH3COOH? H O s bonds = 6 + 1 = 7 H C C O H p bonds = 1 H 21 22 SAMPLE PROBLEM 11.2 Describing the Bond in Molecules PROBLEM: Describe the types of bonds and orbitals in acetone, (CH3)2CO. PLAN: Use the Lewis structures to ascertain the arrangement of groups and shape at each central atom. Postulate the hybrid orbitals taking note of the multiple bonds and their orbital overlaps. SOLUTION: sp2 sp2 sp3 hybridized O O O sp2 H H sp3 hybridized H C H sp2 sp3 C C H H H sp3 2 2 H sp C sp C sp3 C sp2 hybridized C 3 H sp 3 sp 3 H H3 C CH3 sp3 H sp H sp3 p bond s bonds 23 24 6  Exercise H H O' H H C" H C' CH H O' N H O C C CH H HC CH O H a) How many s and p bonds in the molecule? b) What is hybridization for C’, C”, N and O’? 26 25 26 If a molecule MX 3 has zero dipole moment, the sigma bonding orbitals used by M (atomic number < 21) are : (a) pure p (b) sp hybrid (c) sp 2 hybrid (d) sp 3 hybrid Answer: Molecule of MX 3 type having zero dipole moment; then its geometry must be trigonal planar, i.e. hybridization of M will be sp 2. 27 7