Final answer:
Cis fatty acids have hydrogen atoms on the same side of the double bond causing a bent structure and are generally liquid at room temperature, whereas trans fatty acids have hydrogens on opposite sides leading to a linear structure and are often solids.
Step-by-step explanation:
The primary difference between a cis fatty acid and a trans fatty acid lies in the spatial arrangement of hydrogen atoms around the double bonds in their hydrocarbon chains. In a cis fatty acid, the hydrogen atoms are positioned on the same side of the carbon chain, causing a bend or kink in its structure. This kink affects the physical properties of the fatty acid, making it typically liquid at room temperature due to lower intermolecular forces. On the other hand, in a trans fatty acid, the hydrogens are on opposite sides, giving the molecule a more linear structure, which often results in a higher melting point and a solid state at room temperature. Moreover, while cis fatty acids are commonly found in nature, trans fatty acids are mostly generated through industrial hydrogenation processes.