Here's why:

* Elements are pure substances made up of only one type of atom (like hydrogen, oxygen, gold).

* Compounds are formed when two or more different elements chemically combine (like water, which is made of hydrogen and oxygen).

* Mixtures are combinations of substances that are not chemically bonded (like salt and pepper).

Light is electromagnetic radiation. It's a form of energy that travels in waves and can be described by its wavelength and frequency. It's not made up of atoms or molecules like elements, compounds, or mixtures.