Final answer:
Fat molecules contain energy primarily stored in the bonds between carbon and hydrogen atoms; saturated fats have single bonds leading to more compact energy storage, while unsaturated fats have double bonds and less dense energy storage.
Step-by-step explanation:
The energy content of a fat molecule is determined by the types of bonds between carbon (C) and hydrogen (H) atoms within the fatty acid chains. In saturated fats, carbon atoms are bonded to the maximum number of hydrogen atoms possible with only single bonds between carbon atoms. This allows them to pack together tightly, storing energy more densely. Unsaturated fats have one or more double bonds between carbon atoms, which reduces the number of hydrogen atoms attached.
These double bonds introduce kinks or bends in the fatty acid chains, preventing tight packing and resulting in fats that are liquid at room temperature. The presence of these double bonds in unsaturated fats means they contain less energy per unit of weight compared to saturated fats.
Saturated fatty acids have straight chains due to single C-C bonds, allowing them to store energy compactly, while unsaturated fatty acids contain C=C double bonds that create kinks, make the fats less dense in energy and often liquid at room temperature. The number and type of bonds directly affect the melting point and energy content of the fat.