What is the limitation of dobereiners periodic table?

Answer 1

All the elements known at that time could not be arranged as Dobereiner's triad's example: the three elements, nitrogen, phosphorus and arsenic have similar properties. Therefore they can be regarded to form a triad. However, the actual atomic mass if the middle element, phosphorus(P)(31.0u)

is much lower than the average or mean(44.45u)of the atomic masses of nitrogen and arsenic. Thus, these three elements do not constitute a Dobereiner triad in spite of their similar chemical properties.

Answer 2

Dobereiner's Periodic Table only grouped elements in sets of three, known as triads, based on similarities in properties. This limited classification system did not account for all known elements and did not provide a complete framework for understanding the periodic trends of elements. It also didn't establish a clear pattern or arrangement of elements.