Chemical bonding and molecular structure

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Total Questions under the topic: 100

Driving Forces & Definitions:

Main motivation for bonding (achieving stability, primarily the octet rule); definition of valence electrons; processes for stable configuration (electron transfer or mutual sharing).
Ionic Bonding:

Formation via complete transfer of electrons. Favorable conditions: large electronegativity difference. Properties: solubility in polar solvents, solid physical state, high ionic character. Includes calculations like determining percentage ionic character from dipole moment data.
Covalent Bonding:

Formation via mutual sharing of electrons; definition of covalency. Distinction between non-polar vs. polar covalent bonds (based on electronegativity difference Δ χ). Nature of coordinate bonds (dative bonds) where one species acts as a Lewis base (NH₃) and the other as a Lewis acid (BF₃).

2. Molecular Structure and Geometry

VSEPR Theory:

Determining electron geometry and molecular shape based on bond pairs and lone pairs (e.g., Tetrahedral, Trigonal Planar, See-Saw, Square Planar, Bent-T shape). Understanding the influence of repulsion strength order on bond angles (e.g., H₂O’s angle smaller than sp³).
Hybridization:

Identification of hybridization types (sp, sp², sp³, sp³d, sp³d², sp³d³). Relationship between bond angle and s-character (e.g., sp for 180°).
Orbital Theory:

Distinction between σ (sigma) and π (pi) bonds; various overlap types (s-s, s-p, p-p). Nature of angular and radial nodes in specific orbitals (5f,3d).

Bond Parameters:

Relationship between bond length and hybridization/s-character (sp vs. sp² vs. sp³); the order of bond energy (single, double, and triple bonds); and the calculation of bond order for isoelectronic species (N₂, CO, NO⁺).
Dipole Moment (μ):

Definition (μ = q × d); units (Debye, C m); and factors influencing magnitude (molecular symmetry and vector summation/cancellation).
Formal Charge and Resonance:

Calculation of Formal Charge on atoms (e.g., CO₃^2-); understanding why Resonance is required to describe structures; and the nature of the true structure, the Resonance Hybrid.

Polarization (Fajan’s Rules):

Conditions that favor covalent character (small cation and large anion) versus ionic character; effects of cation/anion size on ionic polarization.
Molecular Orbital Theory (MOT):

Correct order of Molecular Orbital (MO) energy levels for homonuclear diatomics (N₂, O₂); calculation of Bond Order (B.O.); determination of magnetic character (Paramagnetic vs. Diamagnetic); and relating B.O. to stability.
Hydrogen Bonding:

Requirements for its existence; distinction between intermolecular and intramolecular H-bonding; and how it affects physical properties (e.g., high boiling point of H₂O and the unusual volume change when ice melts).

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