Dmitri Mendeleev is considered the father of the periodic table. In 1869, he created one of the first recognizable periodic tables that arranged elements based on increasing atomic mass. It included 17 columns with gaps for elements not yet discovered. Later, in 1871, he revised his table to include 8 columns and more accurately predicted properties of undiscovered elements. Today's periodic table arranges elements by atomic number instead of mass and includes all known elements. It categorizes them into metals, nonmetals, and metalloids based on their physical and chemical properties.