Question

what is the basic difference in approach between the Mendeleev periodic law and the modern periodic law

Answer 1

According to Mandeleev Periodic law , elements were arranged by their atomic mass & according to modern periodic law ,elements arranged by their atomic no. in the table.

Answer 2

In the modern periodic table, the elements are arranged in order of increasing atomic no. Mendeleev's table they were arranged in order of increasing atomic weight