Question

What are the Defects of Triad Classification?

Answer 1

Dobreiner, a German Scientist was the first to classify elents into groups. His classification is called as Dobreiner triad.

The defects in his classification:

● A large number of similar elements couldn't be placed in the triad.

● A few dissimilar elements were placed in the triad.

● Dobreiner was only able to classify three triads successfully.

Answer 2

                               Dobereiner's Triads

Dobereiner classified elements into groups of three (triad) where "The Atomic Weight of the middle element was the Average of the other two elements"

Example : Ca (Calcium) , Sr (Strontium) , Ba (Barium)

• Atomic weight of Ca = 40 a.m.u

• Atomic weight of Sr = 88 a.m.u

• Atomic weight of Ba = 137 a.m.u

Here Middle Element is Sr

⇒ 88 = (40 + 137)/2  ⇒ 88 = 177/2 ⇒ 88 = 88

Merits : The main achievement of this classification is that it recognized a relationship between properties of elements and their atomic weights

Drawbacks of this classification : The Drawbacks of this classification of this classification are as follows :-

• Some elements which are dissimilar were being grouped into a triad
• There are many elements that cannot be grouped into triads was proposed by Dobereiner