Cis-trans isomers are like the "left-handed" and "right-handed" versions of molecules. They have the same ingredients but are arranged differently around a double bond (or in a ring structure).

• Alkenes have a carbon-carbon double bond (C=C).
• No rotation can occur around this C=C double bond.
• When the two groups attached to these carbon atoms are different, we can have cis-trans isomers.

🔍 Real-world Analogy: Imagine two people (carbon atoms) holding hands (the double bond). Each person is holding a different object in their free hand (the different groups). If both objects are on the same side, it’s like they’re holding matching bags - this is cis. If the objects are on opposite sides, it’s like they're waving at other friends across them - this is trans.

• Cis-isomer: Both methyl groups (CH₃) are on the SAME side.
• Trans-isomer: Both methyl groups (CH₃) are on OPPOSITE sides.

🔍 Real-world Analogy: Think of the double bond as a river. In the cis-isomer, both ducklings (methyl groups) are on the same side of the river. In the trans-isomer, they're on opposite shores, quacking across the water to each other.