Molecular Structure and Bonding

Paper Code: 
CHY - 101
Credits: 
2
Contact Hours: 
30.00
Max. Marks: 
100.00
7.00
Unit I: 
The Ionic Bond

Introduction, radius ratio rules- calculation of limiting radius ratio values for coordination number 3,4 ,6 and 8; close packing; classification of ionic structures, ionic compounds of the type AX (ZnS, NaCl, CsCl) and AX2 (CaF2-Fluorite), limitations of radius ratio rule; calculation of lattice energy, factors affecting lattice energy, the Born Haber cycle and its application; solvation energy and solubilities of ionic substances; stoichiometric and non stoichiometric defects.
 

7.00
Unit II: 
The Covalent Bond

The Lewis theory, octet rule, explanations for the failure of octet rule,exceptions to octet rule; valence bond theory (Heitler and London approach) and its limitations; resonance; directional character of covalent bond, various types of hybridization ( sp, sp2, sp3, sp3d,sp3d2, dsp2, sp3d3) and shapes of molecules; VSEPR theory,  isoelectronic principle, examples using VSEPR theory, polarizability of ions, Fajan’s rule and consequences of polarization, dipole moment and percentage ionic character in covalent compounds ( electronegativity difference and dipole moment method), bond energy and bond length.
 

6.00
Unit III: 
Molecular Orbital Approach in Covalent Bond

Introduction, LCAO approach, combination of orbitals (s-s, s-p, p-p, non-bonding combination of orbitals), examples of molecular orbital treatment for homonuclear diatomic molecules – H2+, H2, He2, B2, C2, N2, Be2, O2, O2+1, O2-1, O2-2, F2, examples of molecular orbital treatment for heteronuclear diatomic molecules- NO, NO+, CO, CO+, CN molecule, comparison of VBT and MOT.
 

5.00
Unit IV: 
The Metallic Bond

Multicentred bonding in electron deficient molecule; general properties of metals– conductivity, lustre, malleability, ductility, crystal structures; theories of bonding in metals – free electron theory, valence bond theory and band theory – conductors, insulators and semi-conductors; superconductors.
 

5.00
Unit V: 
Weak Interactions

Van der Waal’s forces: ion-dipole forces, dipole-dipole interactions, induced dipole interactions, instantaneous dipole – induced dipole interactions, repulsive forces.
Hydrogen bond: types, theories and properties of H-bond, effects of H-bond on physical properties.
 

Essential Readings: 
  1. A New Concise Inorganic Chemistry; Fifth Edition; J.D. Lee; Blackwell Science, London, 1989.
  2. Inorganic Chemistry; Third Edition; D.F. Shriver and P.W. Atkins; Oxford University Press, New York, 1999.
     
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