Question

State Dobereiner's low of triads? give one example of triads

Answer 1

Answer:

The atomic mass of the middle element was approximately equal to the mean of the atomic mass of the other two elements

e.g.Li,Na,K. 6.9+39.1/2=23.0

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