How did Mendeleev arrange the elements? He left empty places in his periodic table. Why? Explain the limitations of Mendeleev classification

Explanation

a) Mendeleev realized that the physical and chemical properties of elements were related to their atomic mass in a "periodic way and arranged them so that groups of elements with similar properties fell into vertical columns in his table.
b) Gaps were left for undiscovered elements in the Mendeleev.s periodic table.
c) Limitations of Mendeleev classification :
* Position of hydrogen was not justified.
* Increasing order of atomic mass could not be maintained.
* Isotopes have similar chemical properties but different atomic masses, they cannot be given separate places.
* Mendeleev could not explain the cause of periodicty.