Question

what are the demerits of Mendeleev's periodic table?
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Answer 1

Answer:

mendeleev's periodic table demerits are as follows,,

mendeelev listed 70 elements which were known in his period.... as he arranged the periodic table in the increasing order of the atomic number it is the defect

Answer 2

Explanation:

1)The element Cobalt and Nickel have the same whole number atomic mass. as a remite there was an ambiguity regarding their sequence in Mendeleev periodic table. 2)isotopes were Discoverd long time after mendeleev put forh the periodic table. challenge was posed in placing isotopes in Mendeleev periodic table as isotopes have the same chemical properties but different atomic masses. 3)the the rise in the atomic masses does not appear to be uniform when elements are arranged in increasing order of atomic masses it was not possible therefore to prdiect how many elements could be is discoverd between two heavy elements. 4) position of hydrogen hydrogen show similarity with Halogen group for example the molecular formula of hydrogen in H2 while the molecular formula of flurine and chlorine are F2 and cl2 respectively in the same way there us similarity in the chemical property of hydrogen and alkali metal ( group 1 )there is a similarity in the molecular formula of the compounds hydrogen alkali metals formed with chlorine and oxygen on considering the above property it is difficult to decide the correct position of hydrogen whether it is in the group of alkali metals are in the group of halogen