The document summarizes key aspects of the periodic table discovered by Dmitri Mendeleev, including that elements in the same group have similar chemical properties due to their valence electrons. Metals are on the left side of the table, nonmetals on the right, and metalloids divide them. Atomic number generally determines atomic mass, with some variations. The table organizes elements by their similarities and properties. Examples are given of common uses of copper, silver, and gold.