Question

2. Explain
4. Dobereiner's Triads. . answer in point​

Answer 1

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Answer 2

· Dobereiner’s triads were groups of elements with similar properties that were identified by the German chemist Johann Wolfgang Dobereiner.
· He observed that groups of three elements (triads) could be formed in which all the elements shared similar physical and chemical properties.
· Dobereiner stated in his law of triads that the arithmetic mean of the atomic masses of the first and third element in a triad would be approximately equal to the atomic mass of the second element in that triad.
· The first of Dobereiner’s triads was identified in the year 1817 and was constituted by the alkaline earth metals calcium, strontium, and barium. Three more triads were identified by the year 1829.

Triad 1:
This triad was made up of the alkali metals.
Triad Atomic Masses
Lithium 6.94
Sodium 22.99
Potassium 39.1
The arithmetic mean of the masses of potassium and lithium corresponds to 23.02, which is almost equal to the atomic mass of sodium.

Triad 2:
Triad Atomic Masses
Calcium 40.1
Strontium 87.6
Barium 137.3
The mean of the masses of barium and calcium corresponds to 88.7.

Triad 3:
These are halogens.
Triad Atomic Masses
Chlorine 35.4
Bromine 79.9
Iodine 126.9
The mean value of the atomic masses of chlorine and iodine is 81.1.