The two types of pure substances are elements and compounds. A pure substance is that which consists of only one component with distinct chemical and physical properties. Any substance with more than one component is called a mixture.
Elements are the basic building blocks of matter and are each made up of a single type of atom. Atoms cannot be broken down into smaller particles. Examples of elements include calcium, aluminum, potassium, oxygen and hydrogen. On the other hand, a compound is made up of two or more elements whose atoms have chemically bonded in specific proportions. Compounds have distinct properties that differ from those of their individual elements. Water (H2O) is a compound formed by combining hydrogen and oxygen. Common sugar is a combination of carbon, hydrogen and oxygen.