Question

what are the demerits of Mendeleev's periodic table?​

Answer 1

Answer:

Demerits of Mendeleev's Periodic Table :

(a) Mendeleev arranged elements in the ascending order of their atomic masses. There was no fixed position for hydrogen in his periodic table, as it resembled alkali metals as well as halogens.

(b) Elements of higher atomic mass were placed before elements of lower atomic mass. Cobalt with atomic mass 58.93 was placed before nickel with atomic mass 58.71.

(c) Elements having different properties were placed in the same sub group like manganese (Mn) was placed with halogens which had totally different properties

Explanation:

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Answer 2

Answer:

1.Hydrogen resembles both the alkali metals and halogens. But it has been placed with the alkali.

2.The lanthanides and actinides have not been placed in the main body of the table.

3. In his times, many elements, including noble gases, scandium (Eka-boron), Gallium (Eka- Aluminium), Technetium (Eka- Manganese), Germanium (Eka- silicon) weren't discovered. So many empty spaces were left. He even predicted the properties of these missing elements, know as the eka-elements (mentioned above).

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