In hyperconjugation, the sigma electrons of the bond of an alkyl group are delocalised. This group is directly attached to an atom of an unsaturated system. The delocalisation occurs because of a partial overlap of a –s sigma bond orbital with an empty orbital of the bond of an adjacent carbon atom. The process of hyperconjugation in propene is shown as follows:
This type of overlap leads to a delocalisation (also known as no3bond resonance) of the electrons, making the molecule more stable.