Question

Define Dobereiner's Triads.​

Answer 1

Dobereiner was one of the earliest scientists to attempt classification of elements in an orderly manner.

The triads (meaning made of, or related to three) included 3 elements in a row, the arithmetic mean of the atomic masses of the first and last of which would be approximately equal to the one in the middle.

E.g.

Li Na K

6.9 23 39.1

(6.9 + 39.1)/2

is equal to 23.

Answer 2

Dobereriner states that when elements

with similar properties are to be taken 3

at a time and should be arranged in the

ascending order according to their

atomic weights ( similar elements in

same group ) .

Dobereiner's triads states that the

atomic weights of the middle element

is the average of the atomic weights of

the 1st and 3rd elements .

This is only known as Dobereiner's law of triads .

Examples :-

1) let group A

Lithium ---- 7.0

Sodium ---- 23.0

Potassium ---- 39.0

when we do average

7.0 + 39.0 / 2 ===> 46.0 / 2 ===> 23.0