Substances composed of different types of atoms bonded together are called compounds.

Here's why:

* Elements are made up of only one type of atom (like oxygen, gold, or carbon).

* Compounds are formed when two or more different elements chemically combine in a fixed ratio. This means the atoms are held together by chemical bonds, which are forces that arise from the sharing or transfer of electrons.

Examples of compounds:

* Water (H₂O): Two hydrogen atoms bonded to one oxygen atom.

* Salt (NaCl): One sodium atom bonded to one chlorine atom.

* Sugar (C₁₂H₂₂O₁₁): Twelve carbon atoms, twenty-two hydrogen atoms, and eleven oxygen atoms bonded together.

Let me know if you'd like more examples or information!