What are the differences in the modern periodic table?

Main differences between Mendeleev’s Periodic Table and the modern periodic table:

  1. 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).
  2. More elements are in the modern periodic table which have been discovered since Mendeleev’s time. eg. the noble gases (group 0).
  3. There are no gaps. The gaps in Mendeleev’s have been filled by the elements that were discovered.
  4. The transition elements are listed in a separate block where as Mendeleev included them with the other elements.