Which term describes the smallest unit of most compounds that retains the properties of that compound?

The term that describes the smallest unit of most compounds, while retaining the properties of that compound, is a molecule. A molecule is formed when two or more atoms bond together through covalent bonds. These bonds allow atoms to share or transfer electrons, leading to the creation of a distinct entity with its own unique chemical properties. For example, the water molecule (H2O) consists of two hydrogen atoms and one oxygen atom. Its behavior and characteristics are different from the individual atoms that compose it.

In contrast, an atom is the basic unit of matter and the building block of molecules, but it does not represent a compound in and of itself. An ionic bond refers to the electrostatic attraction between oppositely charged ions, which occurs in ionic compounds but does not define the smallest unit of a compound. An element is a pure substance made of only one type of atom, and while it is vital to compounds, it does not represent the smallest unit of compounds that carry their characteristics. Hence, the molecule is the most accurate term for this definition.