Attempts of elements classification: Dmitrii Mendeleev

Mendeleev's periodic table was revolutionary due to its predictive power, leaving gaps for undiscovered elements. His accurate prediction of germanium's properties validated the table's utility, leading to its acceptance. Over time, the table has been refined and expanded by other scientists.

In what way did Mendeleev's approach differ from simply fitting elements into the periodic table?

What corrections and expansions have been made to the periodic table since Mendeleev's time?