Electronic Displacements
- Inductive Effect ($I$): Permanent polarisation of $\sigma$-bonds induced by electronegative atoms ($+I$ / $-I$).
- Resonance Effect ($R/M$): Delocalisation of $\pi$-electrons or lone pairs through conjugated systems.
- Hyperconjugation: Delocalisation of $\sigma$-electrons of $C-H$ bonds of alkyl group with adjacent empty $p$-orbital (No-bond resonance).
- Stability of Carbocations: $3^\circ > 2^\circ > 1^\circ > \text{CH}_3^+$.
