Hyperconjugation

Concept: No-bond resonance involving the delocalization of $$\sigma$$ -electrons of a $$\text{C--H}$$ or $$\text{C--C}$$ bond with an adjacent vacant $$p$$ -orbital or $$\pi$$ -orbital.

Condition: Presence of at least one $$\alpha$$ \text{-hydrogen} relative to a carbocation, free radical, or alkene double bond.

Stability Rule: Stability is directly proportional to the number of $$\alpha$$ \text{-hydrogens}.