* Saturated fats have all the hydrogen atoms they can possibly hold. Each carbon atom in the fatty acid chain is bonded to the maximum number of hydrogen atoms.

* Polyunsaturated fats have at least two double bonds between carbon atoms in their fatty acid chains. These double bonds replace single bonds, and each double bond means two fewer hydrogen atoms are attached.

Think of it like this:

* Imagine a chain of carbon atoms. Each carbon atom can hold up to four bonds.

* In saturated fat, each carbon atom is bonded to four hydrogen atoms (single bonds).

* In polyunsaturated fat, some carbon atoms are double-bonded to other carbons, leaving fewer spots for hydrogen atoms.

This difference in hydrogen atoms leads to a difference in the shape of the molecules:

* Saturated fats are straight chains and tend to be solid at room temperature.

* Polyunsaturated fats have "kinks" in their chains due to the double bonds, making them more liquid at room temperature.

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