Here are examples of a molecule that is a compound and one that is not:

* Compound: Water (H₂O). Water is a compound because it is formed by the chemical combination of two different elements: hydrogen (H) and oxygen (O).

* Not a compound: Oxygen gas (O₂). Oxygen gas is made up of two oxygen atoms bonded together. Since it is made of only one type of element, it is not a compound. It is considered a diatomic element.