A pure substance where atoms of two or more elements are chemically bonded to one another is called a compound.

Here's why:

* Pure substance: This means the substance is made up of only one type of molecule or atom.

* Chemically bonded: The atoms of different elements are held together by chemical bonds, forming a new and distinct substance with properties different from the original elements.

Examples of compounds:

* Water (H₂O): Composed of hydrogen and oxygen atoms.

* Sodium chloride (NaCl): Composed of sodium and chlorine atoms.

* Carbon dioxide (CO₂): Composed of carbon and oxygen atoms.