State two limitations of Mendeleev Periodic Table.
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Solution
Principle of Mendeleev's periodic table:
Mendeleev's periodic law states that the physical and chemical properties of elements are a periodic function of their atomic weights.
According to Mendeleev periodic physical and chemical properties of elements depend on their atomic weight such that on arranging elements in increasing order of atomic weight, elements with similar properties are repeated after regular intervals of increasing atomic weight.
Limitations of Mendeleev's periodic table:
Elements with large differences in properties were included in the same group. For example, hard metals like copper and silver were included along with soft metals like sodium and potassium.
No proper position could be given to the element hydrogen. In the periodic table, the location of hydrogen is uncertain. It was put with alkali metals within 1A class, but certain hydrogen properties are close to those of halogens. So, it can also be put for halogens in the band.