Whose periodic table first arranged the elements by atomic weight and predicted missing elements?

Dmitri Mendeleev is credited with creating the first widely successful periodic table in 1869. He arranged the known elements largely by increasing atomic weight while grouping elements with similar chemical behavior. What made his table remarkable was that he deliberately left gaps for elements not yet discovered, including eka-silicon and eka-aluminum. Those predictions were later confirmed by the discoveries of germanium and gallium, among others. His work became the foundation of the modern periodic table.