Question

Which of the following statements are true regarding Döbereiner's classification of elements?

(More than one option is correct)

• A. Döbereiner classified all the elements known at that time into triads.
• B. Every eighth element had properties similar to that of the first element in Döbereiner's classification.
• C. The mass of middle element was roughly the average of atomic masses of other two elements in the triad.
• D. Elements in a triad show similar properties.

Answer 1

Answer: (C), (D)

Elements in a triad show similar properties.

Dobereiner stated that when elements with similar properties are arranged in a group of three (triad) in the increasing order of their atomic mass, the atomic mass of the middle element is roughly the average of the atomic masses of the other two elements. He could form only 5 triads out of the discovered elements.
However, in Newlands' octave every eighth element had properties similar to that of the first element.