Main differences between Mendeleev’s Periodic Table and the modern periodic table:
- 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. eg. the noble gases (group 0).
- There are no gaps. The gaps in Mendeleev’s have been filled by the elements that were discovered.
- The transition elements are listed in a separate block where as Mendeleev included them with the other elements.