In the modern periodic table, the physical & chemical properties of the elements are changed to the periodic function of their atomic numbers instead of atomic weight which solves the problem with isotopes. All isotopes of some element represented by the same atomic number. All the gaps of Mendeleev's periodic table are filled by discovering new elements. The column for inert gases was developed and all groups have sub-groups. In this way, the modern periodic table removes all the demerits of Mendeleev's periodic table.