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 atomci weight while Modern periodic law states that physical and chemical properties of elements are a periodic funtions of their atomic numbers. Thus, the basic difference in approach between the two laws is the change in the basis of classification of elements from atomic weight to atomic number.