I'm going to explain what a pure substance is in this section. Pure substances are defined as substances that are made of only one type of atom or only one type of molecule. There are 2 kinds of pure substances, an element and a compound.
A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into its elements or a combination of the two. A couple of several examples of compounds are water , salt , methane and sugar .
An element is a pure substance which cannot be broken down by further chemical techniques. Several examples of elements are Hydrogen,Carbon, and Oxygen.