Monday 18 September 2017

Periodic Classification of Element

Periodic Classification of Element


Question-1
Did Dobereiner’s triads also exist in the columns of Newlands Octaves? Compare and find out.
Solution:
Yes, Dobereiner’s triads also exist in the columns of Newlands Octaves. For example, the second column of Newlands classification has the elements lithium (Li), sodium (Na) and Potassium (K), which constitute a Dobereiner’s triad.
Question-2
What were the limitations of Dobereiner’s classification?

Solution:
All the known elements could not be arranged in the form of triads. For very low mass or for very high mass elements, the Dobereiner’s triads are not applicable. Take the example of F, Cl and Br. Atomic mass of Cl is not an arithmetic mean of atomic masses of F and Br. As the techniques for measuring atomic masses accurately, improved, the Dobereiner’s triad was unable to remain strictly valid.
Question-3
What were the limitations of Newland’s Law of Octaves?

Solution:
It was not valid for elements that had atomic masses higher than Ca.When more elements were discovered, such as elements from the noble gases such as He, Ne, Ar, they could not be accommodated in his table.

PERIODIC CLASSIFICATION OF ELEMENT

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