Question

difference between modern periodic table and mandeleev periodic table​

Answer 1

Modern periodic table is based on atomic number

Mendeleev periodic table is based on atomic masses

Answer 2

In the modern periodic table, the elements are arranged in order of increasing atomic number. (In Mendeleev's table, they were arranged in order of increasing atomic weight). More elements are in the modern periodic table which have been discovered since Mendeleev's time.