Final answer:
1,3-butadiene is more stable than 1-butene due to the delocalization of electrons across its conjugated double bonds, resulting in a planar molecule with sp² hybridization and a smaller HOMO-LUMO energy gap.
Step-by-step explanation:
1,3-butadiene is more stable than 1-butene because of the delocalization of the electrons in its structure. This delocalization arises due to the conjugation of the double bonds within the 1,3-butadiene molecule. In contrast to the isolated double bond in 1-butene, 1,3-butadiene's conjugated system allows the π (pi) electrons to be shared across multiple atoms, which reduces the overall energy of the molecule and increases its stability.
The presence of conjugated double bonds, as seen in 1,3-butadiene, is a significant stabilizing factor. The sp² hybridization of the carbon atoms in such a configuration also contributes to the molecule's stability, giving it a planar structure which is energetically more favorable. Moreover, 1,3-butadiene has a smaller HOMO-LUMO energy gap, resulting from its conjugated system, which further stabilizes the molecule and allows it to absorb UV light with a wavelength of 217 nm, indicating an extended system of electrons.
These properties associated with delocalized electrons and conjugation are very important in organic chemistry and can be observed in many natural substances and industrial chemicals, as is the case with 1,3-butadiene, which is widely used for the production of synthetic rubber. The concept of isomerism, as with 1-butene and 2-butene having different properties despite the same molecular formula (C4H8), also plays a key role in understanding the diverse chemical behavior of organic compounds.