Question

What are the basic differences between Mendeleeff's periodic table and modern periodic table?

Answer 1

The differences can be listed as:
(i) Mendeleeff's periodic table was based on atomic weight whereas modern periodic table was based on atomic number.
(ii) Mendeleef's periodic table consists of 8 groups and 7 periods whereas modern periodic table consists of 18 groups and 7 periods.
(iii) Mendeleeff's periodic table included 63 elements, while the modern table consists of 109 elements.