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Chemical Bonding and Molecular Structure BY YUVASSREE - Coggle Diagram
Chemical Bonding and Molecular Structure
BY YUVASSREE
Introduction
Need for bonding → atoms combine to gain stability
Octet rule → 8 electrons in outer shell = stable configuration
Limitations → odd-electron molecules (NO, NO₂), incomplete octet (BeCl₂, BF₃), expanded octet (SF₆, PCl₅)
Types of Chemical Bonds
Ionic bond → electron transfer, formation of ions, strong electrostatic attraction (NaCl, CaCl₂)
Covalent bond → sharing of electrons, directionality, strength (CH₄, O₂, N₂)
Coordinate bond → one atom donates lone pair, other accepts (NH₄⁺, CO)
Theories of Bonding
Valence Bond Theory → bond by overlap of orbitals, types: σ (head-on), π (sideways), localized concept
Molecular Orbital Theory → atomic orbitals combine → bonding & antibonding orbitals, bond order = (Nb – Na)/2, explains magnetism (O₂ paramagnetic)
VSEPR Theory
Electron pairs repel → molecules adopt geometry to minimize repulsion
Shapes:
Linear → BeCl₂
Trigonal planar → BF₃
Tetrahedral → CH₄
Trigonal bipyramidal → PCl₅
Octahedral → SF₆
Lone pairs distort shape (NH₃ → trigonal pyramidal, H₂O → bent)
Hybridisation
Mixing of atomic orbitals → new equivalent hybrid orbitals
Types:
sp (linear, BeCl₂)
sp² (trigonal planar, BF₃)
sp³ (tetrahedral, CH₄)
sp³d (trigonal bipyramidal, PCl₅)
sp³d² (octahedral, SF₆)
Explains equivalent bond angles and geometry
Hydrogen Bonding
Attractive force between H (bonded to F, O, N) and lone pair of another electronegative atom
Types:
Intermolecular → H₂O molecules (responsible for high boiling point)
Intramolecular → o-nitrophenol (affects solubility)