Debonair tried

 During the middle of 18th century most of the chemist reallized a need to arrange the know by that time.  The classification of elements was necessary to identify the properties of various known element and to know the elements having similar physical properties. 

To start with classification , Debonair was the first scientist who introduced the classification

He identify the atomic masses of various element and arranged three elements in such a way that the average of atomic masses of first and third elements comes out to be nearly that atomic mass of middle element. Later on this triplet  were known as DOBERNIER TRIADS.

•Example = 

• Dobernier made a triad of Li,Na,K with atomic mass 7,23 and 39 respectively. When the atomic mass of Li and K were added and their average was taken it come equal to atomic mass of Na which were the middle element.

Limitation of Dobernier Triad

• Debonair triad was limited to some known element only.

• He is selected only those elements which followed his low of average of atomic masses.

• He could not justify the logic behind the element which were left.

• Thus the DOBERNIER TRIAD very failed to classify all the known element by that time.

• This lead  the discovery of new law to arrange known elements.