Here's why:

* Elements are pure substances that cannot be broken down into simpler substances by chemical means. Examples include sulfur (S) and oxygen (O).

* Compounds are formed when two or more different elements chemically combine in a fixed ratio.

Sulfur oxide is made up of sulfur (S) and oxygen (O), combined in a specific ratio. For example, sulfur dioxide (SO₂) has one sulfur atom and two oxygen atoms.