Here's why:
* Definition of a compound: A compound is a substance formed when two or more different elements are chemically bonded together.
* Ozone's composition: Ozone is made up of only oxygen atoms, but it's three oxygen atoms bonded together.
So, while ozone is made up of the same element, the fact that it has multiple atoms of that element chemically bonded together makes it a compound, not just a single element.
It's easy to get confused because we often talk about "oxygen" in the air, which is mostly diatomic oxygen (O₂), but ozone is a distinct molecule with different properties and roles.
