What is a molecule that consists of two or more different elements called?

A molecule made up of two or more different elements is referred to as a compound. This definition comes from the fact that compounds are formed when atoms of different elements chemically combine in fixed proportions, resulting in a substance that has distinct properties separate from those of its constituent elements. For instance, water (H₂O) is a compound made up of hydrogen and oxygen atoms.

In contrast, an element is a pure substance that cannot be broken down into simpler substances by chemical means and consists of only one type of atom. A mixture involves two or more substances that are physically combined, where each substance retains its individual properties. An isotope refers to atoms that have the same number of protons but different numbers of neutrons, which relates specifically to variations of individual elements rather than combinations of different elements.