What is Dobereiner’s law of triads? Explain with the help of one example of a Dobereiner’s triad.

According to Dobereiner’s Law of triads, when elements are arranged in increasing order of their atomic masses, a group of elements with similar chemical properties is obtained. These are called triads. The atomic mass of the middle element is equal to the arithmetic mean of the atomic masses of the other two elements.

For example, In the alkali metal group (Dobereiner's triad), Lithium is the 1st element, sodium is the middle element whereas potassium is the 3rd element of the triad.