Question

what are Dobereiner's triads? Explain with an example

Answer 1

DOBEREINER'S TRAIDS

TRAIDS are the group of 3-elements having similar properties arranged in the order of increasing atomic masses

According to Dobereiner the atomic mass of middle element is approximately equal to the arithmetic mean of remaining two

EXAMPLE

Li Na K AM=( 7+39)/2=23

7 23 39

Cl Br I AM=( 35.5+127)/2= 81.5

35.5 80 127

Ca Sr Ba AM=(40+137)/2=88.5

40 88 137

Answer 2

Answer:

                               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

Explanation: