Question

List any three observation which posed a challenge to Mendeleev 's periodic law
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Answer 1

Answer:

in mandeleev periodic table the elemens were place at the perfect postion as per the dobreiner said that thaere will be no othe elements will be found after his periodic table but, mandeleev proved him wrong also he told so that there will be more elements are gonna to be found so in many places he has left gap between the elements where the new elements are going to be placed

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Answer 2

Answer:

1) why he changed the place of cobalt and nickel ..

2) Hydrogen didn't find a suitable place ..

3) His periodic law .. properties of element are a periodic function of their atomic weight...

Explanation:

Explanation of point 3

The elements were not increasing by a perfect number and as atomic weight (mass no.) is fractional there can be any point for example fraction can be 1.22 , 1.23232 this created a problem ..

Bonus point

4) Isotopes were placed in same place ( but according to MENDELEEV'S theory they should be arranged according to their atomic weight ) for eg ----------1 2

H. H

1. 1