* Compound: A substance formed when two or more different elements are chemically combined in a fixed ratio.

* Element: A pure substance that cannot be broken down into simpler substances by chemical means.

* Mixture: A combination of two or more substances where each substance retains its own properties.

Ice (H₂O) is formed by the chemical combination of two hydrogen atoms and one oxygen atom. It has a fixed ratio of these elements, and its properties are distinct from the individual elements.

Here's why it's not a mixture:

* Ice doesn't contain separate components that you can easily isolate (like sand and water).

* The hydrogen and oxygen in ice are chemically bonded, meaning they've formed a new substance with its own unique properties.

Let me know if you have any other questions!