What is defined as the smallest division of a compound that can exist in a natural state?

The smallest division of a compound that can exist in a natural state is a molecule. A molecule is formed when two or more atoms chemically bond together, and it retains the chemical properties of the compound. For example, a water molecule consists of two hydrogen atoms bonded to one oxygen atom (H₂O), and this arrangement defines the properties of water.

In contrast, a substance refers to a form of matter that has a specific composition and distinct properties, but it does not necessarily represent the smallest unit. A mixture is a combination of two or more substances that are not chemically bonded, retaining their individual properties, while an element is a pure substance that consists of only one type of atom. Thus, only the molecule represents the smallest discrete unit of a compound with defined chemical characteristics.