Question

merits of Mendeleev's periodic table and
Demerits of Mendeleev's periodic table

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Answer 1

Answer:

merits: 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.

2) demerits:He was unable to locate hydrogen in the periodic table.

Increase in atomic mass was not regular while moving from one element to another. ...

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

Answer 2

Answer:

(1) Mendeleev arranged the elements (known at that time) in an increasing order of their atomic masses.

(2) The serial or ordinal number of an element in this order was referred to as atomic number.

(3) The periodic table has vertical columns called groups and horizontal raws (now called as periods.)

(4) Properties in a period showed gradual change from left to right, whereas the elements with similar properties were arranged in the same group

(5) He left some gaps corresponding to certain atomic numbers in the periodic table to maintain periodicity of the properties, Newly discovered elements fitted into the gaps with their properties as predicted by the Mendeleev's periodic law.

(6) Inert gases, discovered in later years could be accomodated in this periodic table by creating an additional group.