### Concept Map: Bonding Framework
```mermaid
graph TD
A[Chemical Bonding] --> B[Ionic Bonding]
A --> C[Covalent Bonding]
B --> D[Born-Haber Cycle\n$\Delta Hf$ = $\Delta Hs$ub + IE + ½$\Delta Hd$iss + EA + U]
B --> E[Fajan's Rules\nSmall cation + Large anion\n= More covalent character]
C --> F[VSEPR Theory\nSN = σ-bonds + lone pairs]
C --> G[Hybridization\nSN 2→sp ... SN 6→$sp^{3}$$d^{2}$]
C --> H[MOT\nBO = Nb-Na / 2]
F --> I[Molecular Shape\nRemove lone pairs from\nelectron geometry]
H --> J[$O_{2}$ Paramagnetic\n2 unpaired $e^{-}$ in π*2p]
```
### VSEPR Shape Decision Table
| Lone Pairs on Central Atom | SN=4 Shape | SN=5 Shape | SN=6 Shape |
|---|---|---|---|
| 0 | Tetrahedral (109.5°) | Trigonal bipyramidal | Octahedral (90°) |
| 1 | Trigonal pyramidal (~107°) ↓ | See-saw (~90°/120°) ↓ | Square pyramidal (~90°) ↓ |
| 2 | Bent (~104.5°) ↓↓ | T-shape (~90°) ↓↓ | Square planar (90°) ↓↓ |
| 3 | — | Linear (180°) ↓↓↓ | — |
(↓ = bond angle compressed relative to ideal by lone pair repulsion)
### MO Energy Level Comparison
| Feature | Z ≤ 7 ($B_{2}$, $C_{2}$, $N_{2}$) | Z > 7 ($O_{2}$, $F_{2}$) |
|---|---|---|
| 2p MO order | π2p **below** σ2p | σ2p **below** π2p |
| Key difference | π2p fills first (mixing) ↑ | σ2p fills first (normal) ↑ |
| Affected BO | $N_{2}$ BO = 3 (correct only with mixing order) | $O_{2}$ BO = 2 |
| Magnetism | $N_{2}$ diamagnetic | $O_{2}$ paramagnetic |
### Dipole Moment: Zero vs Non-Zero
| μ = 0 (symmetric) | μ ≠ 0 (asymmetric or lone pair) |
|---|---|
| C$O_{2}$ — linear | $H_{2}O$ — bent (lone pairs) |
| $BF_{3}$ — trigonal planar | $NH_{3}$ — pyramidal (lone pair) |
| $CCl_{4}$ — tetrahedral | $CHCl_{3}$ — tetrahedral but asymmetric bonds |
| $SF_{6}$ — octahedral | S$O_{2}$ — bent (lone pair) |
### Born-Haber Cycle for NaCl (Energy Ladder)
```
Na(g) + ½$Cl_{2}$(g) ──(+121 kJ ½$\Delta Hd$iss)──► Na(g) + Cl(g)
↑ +108 kJ (sublimation) ↓ −349 kJ (EA)
Na(s) + ½$Cl_{2}$(g) $Na^{+}$(g) + $Cl^{-}$(g)
↑ $\Delta Hf$ = −411 kJ ↓ U = −787 kJ
Na(s) + ½$Cl_{2}$(g) ←──────── NaCl(s)
```
$$U = \Delta H_f - \Delta H_{sub} - \frac{1}{2}\Delta H_{diss} - IE - EA = -787 \text{ kJ/mol}$$$
Part of PC-03 — Chemical Bonding & Molecular Structure
Chemical Bonding & Molecular Structure — Visual Guide
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