Periodic Classification of Elements

Class: X

Chapter Name: Periodic classification of elements

Dobereiner’s triads: Johann Wolfgang Dobereiner, a German chemist, classified the known elements in groups of three elements on the basis of similarities in their properties. These groups were called triads.

 Characteristic of Dobereiner’s Triads:

a. Properties of elements in each triad were similar.

b. Atomic mass of the middle elements was roughly the average of the

atomic masses of the other two elements.