Question

what are the demerits of Mendeleev periodic table ?

Answer 1

ANSWER :

The demerits of the periodic table given by Mendeleev are :

1. He could not place the element Hydrogen in appropriate position in the periodic tabular form

2. There was no regular trend in increasing of atomic mass when moved along the elements.

3. More elements was yet to be known.

4. The isotopes were found later which failed to comply with the periodic table.

Answer 2

He was unable to locate hydrogen in the periodic table.

Increase in atomic mass was not regular while moving from one element to another. Hence, the number of elements yet to be discovered was not predictable.

Later on, isotopes of elements were found which violated Mendeleev’s periodic law.