Question

one advantage and disadvantage of these three dobireer , new land, mandellev ​

Answer 1

Answer:

Dobereiner's triads:

• the atomic mass of middle element of the triad was the average of the other two elements of the triad.

limits:

• The rule of average atomic mass only applies till  group B elements.

Newland's Octaves:

• every eighth element has properties similar to the first element.

Limits:

• Rule only applicable till calcium.

Mendeleev periodic table:

• Arranged according to atomic masses.

Limits:  

• He did not follow his own rule in places. eg: nickel and cobalt