Question

Pleased explain this in full methods​

Answer 1

Answer:

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Explanation:

This method was used in older times when the elements were classified according to their atomic masses as atomic weight was considered as the fundamental property of classification.

According to the Law of triads, the elements were classified into a group of 3 such that the atomic weight of the middle element is the average of the other two elements.

The triad included Lithium, Sodium and Potassium:

So, the atomic weight of Sodium = Average of atomic weights of Lithium and Potassium

Weight of Sodium = (7 + 39)/2 = 23