Question

What were the limitations of Dobereiner's classification?

Answer 1

Dobereiner's classification:

• Dobereiner classified the elements into triads such that “the atomic weight of the middle element of the triad is approximately equal to the arithmetic mean of the atomic masses of the first and third elements.”
• For example, $\mathrm{Li}(6.94),\mathrm{Na}(22.99),\mathrm{K}(39.1)$

Limitations of Dobereiner's classification:

• He could find only three triads.
• The classification could not be applied to all the groups or elements.
• It was not applicable to the elements of very low or high atomic masses.