Dmitri Mendeleev is known for developing the periodic table of elements in the 19th century. His innovative approach arranged the known elements based on their atomic mass and properties, revealing periodic trends and relationships among them. Mendeleev's table allowed for the prediction of undiscovered elements and their properties, significantly advancing the field of chemistry. His work laid the foundation for the modern periodic table, which is now organized by atomic number rather than atomic mass. Mendeleev’s contributions are considered essential for the scientific understanding of chemical behavior and the organization of elements.