Question

demerits of dobernier traid , Newland and Mendeleev​

Answer 1

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The arrangement of elements in tabular form was provided by Newlands law of Octaves. Newlands law of octave was the first logically basis on the atomic weight. Demerits of dobereiner's triads system: - This system fails because it does not hold good for all the elements discovered till date time.

Answer 2

Explanation:

1.demerits of Dobereiner’s classification:

Dobereiner could find only three triads; .i.e total of 9 elements only.

However the total number of elements were more than that of those encompassed in Dobereiner’s Triad.

Thus, Dobereiner’s could not be classify most of the elements known at that time.

2.demerits of Newland's law of octaves are as follows:

There was no proper place for hydrogen.

Transition elements were not considered for octaves.

The observation made by Newland does not hold well for those elements which lying beyond Ca. After Calcium,every eighth element did not possess properties similar to that of the first.

The elements that were discovered later could not be fitted into the law of octaves.

3.Demerits of Mendeleev Periodic Table

He was unable to locate hydrogen in the periodic table.

Increase in atomic mass was not regular while moving from one element to another. Hence, the number of elements yet to be discovered was not predictable.

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