Question

compare and contrast the arrangement of elements in mendeleevs periodic table and the modern periodic table

Answer 1

1. Mandeleev's periodic table was based on the order of increasing atomic mass while Modern periodic table was based on increasing atomic number.
2. Mandeleev's periodic table could not find the valid reason of the position of hydrogen while modern periodic table gave a valid reason for the same.
3. Mandeleev's could not explain the concept of isotopes while it was explained by modern periodic table.