What was Dmitri mendeleevs major contribution?
Dmitri Mendeleev's major contributions was that he created the periodic law and he also created the first approved periodic table!
Dmitri Mendeleev created the first periodic table of elements. Dmitri Mendeleev presented his periodic table of the elements based on increasing atomic weight on March 6, 1869, in a presentation to the Russian Chemical Society. While Mendeleev's table was the first to gain some acceptance in the scientific community, it was not the first table of its kind.