* Atoms are the fundamental building blocks of matter. They are the smallest unit of an element that retains the chemical properties of that element.

* Molecules are formed when two or more atoms bond together. These atoms can be of the same element (like in oxygen gas, O₂) or different elements (like in water, H₂O).

* Compounds are a specific type of molecule formed when two or more *different* elements bond together. For example, water (H₂O) is a compound because it's made of hydrogen and oxygen.

In short:

* Atoms make up molecules.

* Molecules can be either elements (like oxygen, O₂) or compounds (like water, H₂O).

Let me know if you have any other questions!