The periodic table organizes all known elements by their chemical properties. Dmitri Mendeleev created the periodic table to show the repeating patterns of elements. The periodic table displays each element's atomic number, symbol, and atomic weight. It can be used to determine the number of protons, electrons, and neutrons in an element. An element is a pure substance made of only one type of atom that cannot be broken down further. A compound is formed by a chemical bond between two or more elements. A mixture involves substances mixed together but not chemically bonded.