Final answer:
Dmitri Mendeleev is renowned for creating the periodic table, where he also predicted the existence of then-unknown elements, confirming the validity of his periodic law. Option 1.
Step-by-step explanation:
Dmitri Mendeleev is famous for developing the periodic table of the elements. In 1869, he published a table that arranged the elements according to increasing atomic mass and highlighted their periodic properties option 1. Mendeleev's insights extended beyond just the organization of known elements; he predicted the existence of unknown elements that would fit into his table, effectively forecasting their properties. When elements like gallium and germanium were discovered and matched his predictions, the scientific community widely accepted his periodic table. Mendeleev's contributions are so significant that element number 101, discovered in 1955, was named mendelevium in his honor.