What were the limitations of Dobereiner's classification?
Limitations of Dobereiner’s classification of elementsare as follows:
- All known elements could not be classified into groups of triads on the basis of their properties
- Not all groups obeyed the Law of Triads. For example, nitrogen family does not obey the Law of Triads.
Average mass of nitrogen and arsenic =
In this case, the mass of phosphorus is not equal to the average mass of the other two elements i.e., nitrogen and arsenic. Hence, the elements of this group do not obey Dobereiner’s Law of Triads.
Hope it is clear to you.
He could only classify three triads from the elements discovered at that time. Many chemically similar elements like nitrogen, phosphorus and arsenic couldn't prove the validity of dobereiner theory of triads. Many elements having different chemical properties like carbon, nitrogen and oxygen couldn't verify his theory of triads. Hope this answer help you