Question

With respect to the merits of the Mendeleev periodic table answer the following question.

Why did he leave gaps in his periodic table?

Answer 1

1. In Mendeleev, periodic table elements were arranged based on increasing atomic mass. During Mendeleev, only 63 elements were known so after studying the properties of elements he arranged them into vertical columns called groups and horizontal rows are called periods.
2. When Mendeleev made his periodic table, he realized that many elements are not known at that time and yet to be discovered. So, left gaps in his periodic table for such elements and also predicted their properties.
3. He named the undiscovered element as eka-boron which was later discovered as Scandium, eka-aluminum was later discovered as Gallium, and eka-silicon was later discovered as Germanium.