Question

state the anomalies of dobenriers law of triads

Answer 1

First:
Doberenier could only find four triads at that time. All those elements could not be classified as Doberenier’s triads.

Second:
This was a major drawback of Doberenier’s triads. He stated that when three elements of same chemical properties were arranged in order of their increasing atomic masses, the sum of first and third element was rougly the average of the middle element.

But, three elements nitrogen, phosphorus and arsenic have same chemical properties, but these three elements do not follow Doberenier’s rule.
Atomic mass of nitrogen is 14 u and that of arsenic is 74.9 u but their average is 14+74.9/2= 44.45 u which is much higher than atomic mass of phosphorus i.e, 31 u.

So, Doberenier’s triads could not be used.

Hope it helps☺☺