Question

What is the principle of Mendeleev's periodic table? Write their merits and limitations.​

Answer 1

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• 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.

Merits of Mendeleev's Periodic Table:

• Mendeleev was first to properly arrange and classify all elements and was able to explain the periodicity in their chemical properties.
• Mendeleev left some gaps for undiscovered elements. He predicted that some elements would be discovered in future. He also predicted properties of those undiscovered elements.

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Answer 2

Explanation:

Some gaps were left for the elements yet to be discovered. Thus, if a certain new element is discovered, it can be placed in a new group without disturbing any existing group. He was unable to locate hydrogen in the periodic table. Increase in atomic mass was not regular while moving from one element to another.