Question

Without knowing the electronic configurations of the atoms of elements Mendeleeff still could arrange the elements nearly close to the arrangements in the Modern periodic table. How can you appreciate this?

Answer 1

1. Mendeleeff took consideration about chemical properties while arranging the elements. So the arrangement of elements is close to arrangement of elements in Modern periodic table. 

2. For this, he violated his periodic law. 

3. He left some gaps for elements, later those elements are discovered. 

4. So the efforts of Mendeleeff should be thoroughly appreciated