What is the basic difference in approach between the Mendellev's peridic law and the Modern periodic law?

Explanation

Mendeleev Periodic Law states that the physical and chemical properties of the elements are a periodic function of their atomic weigths while Modern Periodic Law states that physical and chemical Properties of elements are a periodic function of their atomic numbers . thus the basic differece in approach between Mendeleev's Periodic Law and Modern Periodic Law is the change in basis of classification of elements from atomic weight to atomic number.