Final answer:
An element is the substance that consists of only one kind of atom, making it the simplest form of matter and listed on the Periodic Table of the Elements.
Step-by-step explanation:
The substance that can consist of only one kind of atom is an element. An element is a pure substance made up of only one type of atom, such as hydrogen or gold, and cannot be broken down into a simpler substance by chemical means. This is opposed to a compound, which consists of two or more types of atoms, or a mixture, which may contain more than one kind of pure substance. Elements are listed on the Periodic Table of the Elements and are the simplest forms of matter. When we consider whether a substance is an element, a mixture, or a compound, we analyze its composition; an element will have a uniform composition consisting only of the same type of atom.