Molecular Structure and Bonding

Paper Code: 
CHY- 101
Credits: 
02
Contact Hours: 
30.00
Max. Marks: 
100.00
Objective: 

To learn molecular structure, types of bonding in main group elements and basics of conductors, semiconductors and superconductors.

Pre requisite : Introductory study of different types of bonding and their general properties mentioned in semester I.
 

7.00
Unit I: 
The Ionic Bond

Introduction, size effects, 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+, CO-,  CN, 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.

 

References: 
  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.
Academic Year: 
2018-2019
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