Question

Mendeleev's periodic table also suffered from a lot of defects. Answer the following questions in keeping in mind the defects of Mendeleev's periodic table.

Why was the hydrogen not given a definite position?

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. Although Mendeleev resolved many of the previous limitations in previous arrangements but is suffered from some limitations such as:

Hydrogen had no fixed position in Mendeleev's Periodic Table because it resembles alkali metals by forming positive ions and resembles halogens by forming the diatomic molecule. So, it was placed above both the groups and could not be given a fixed position in Mendeleev’s Periodic Table.