Question

Q. 10. What is a Doboroinor's triads ? Explain​

Answer 1

Answer:-

Dobereiner law of Triads:-

• Dobereiner law of Triads states that, In a group of three elements ; the atomic weight and properties of the middle element is the arithmetic mean of atomic weights of the first and third elements.

• The work "triad" means "A group of three elements".

• This law mostly depends on the atomic weight of an element

Examples:-

1) Li (Lithium) , Na(Sodium) , K (Potassium).

• Atomic weight of Li = 7 a.m.u
• Atomic weight of Na = 23 a.m.u
• Atomic weight of K = 39 a.m.u

⟶ 23 = (7 + 39) / 2

⟶ 23 = 46/2

⟶ 23 = 23

Drawbacks of Dobereiner's triads:-

• Dobereiner couldn't explain his law for all the elements which were existed.

• Dissimilar elements (in their properties) were grouped in a triad.

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