Who made the modern periodic table?
The modern Periodic Table was developed by Dimitri Mendeleev, 1834-1907.
Mendeleev was a professor of chemistry at insititutions in St Petersburg. At the time of his work there were 50-60 elements known, and new elements were discovered year by year. Mendeleev classified the then known elements into Tables based on atomic mass, which also reflected known chemical properties, and created the first Periodic Table. Apparent gaps, or discontinuities in the then Table were later filled by the discovery of new elements.
The discovery of fundamental subatomic particles, protons, electrons, and neutrons, which postdated Mendeleev, showed just how insightful Mendeleev's idea of periodicity was. Elements could be organized on the basis of atomic number, and their place on revised Tables were good predictors of their properties and chemistry.