Stereoisomerism in Alkenes?

📌 CONCEPT: Stereoisomerism in alkenes refers to the phenomenon where molecules with the same molecular formula and functional group exhibit different physical properties due to differences in the arrangement of atoms in space.

📐 RULE / FORMULA: The key principle behind this phenomenon is the presence of a double bond in alkenes, which leads to the formation of cis and trans isomers.

💡 WORKED EXAMPLE: Consider 2-butene, which exists as a mixture of cis and trans isomers. The cis isomer has the same molecular formula (C4H8) and functional group (alkene) as the trans isomer, but they differ in the arrangement of atoms in space. As a result, the cis isomer has a higher boiling point and melting point compared to the trans isomer due to its more compact structure.

⚠️ COMMON MISTAKE: Students often mistakenly believe that the physical properties of cis and trans isomers will be identical due to their identical molecular formula and functional group, when in fact the arrangement of atoms in space plays a crucial role in determining their physical properties.