What was the problem of Dobereniners Traids?

Explanation:

Limitations of Dobereiner's Triads

The identification of new elements made this model obsolete. Newly discovered elements did not fit into the triads. Only a total of 5 Dobereiner's triads were identified. Even several known elements did not fit into any of the triads.

The question is incomplete, the complete question is;

Determine whether each melting point observation corresponds to a pure sample of a single compound or to an impure sample with multiple compounds.

Experimental melting point is BELOW literature value

Experimental melting point is CLOSE to literature value

WIDE melting point range

NARROW melting point range

narrow melting point-pure sample of a single compound

experimental melting point is close to literature value-pure sample of a single compound

wide melting point range-impure sample of multiple compounds

experimental melting point is below literature value-impure sample of multiple compounds

Explanation:

The experimental melting point of a pure single compound is sharp and extremely close to the melting point of the substance as recorded in the literature. Usually, a pure substance melts within a narrow range of temperatures.

Impure samples of multiple compounds melt over a range of temperatures. Also if the experimental melting point is well below the record in literature, then the sample is contaminated by other compounds.