Earlier attempts of classification of Elements

Johann Dobereiner Triad model

The first attempt on classification of elements have no definite proof as early man started to classify elements based on his needs. But a scientific method of classification was first introduced by the German chemist Johann Dobereiner in 1829. He classified the elements to groups of three. It should be noticed that there was only less number of elements at that time and many were not discovered. A classification method at that time therefore really deserve appreciation. Dobereiner thus created a law based on his classification and was called Law of Triads.The name triads came as his classification included elements in a group of three. He also noticed that there was relation in the classified group. The middle element, ie, the second element was having somewhat an atomic mass which was equal to the average mass of other two elements in the group. This was the basis of Law of Triads.

After the long list of classifications the works of this two scientists caused an impact on scientific world. Both came up with same work but Mendeleev was the one with dominance. These 2 personalities are given great respect in chemical world for their contributions. They worked independently and was working on the same method of classification. Dmitri Mendeleev, the German chemist was the first to publish. So the credit goes to him. The basis of their classification was increasing order of atomic weights itself. The difference was the consideration of other physical properties like melting point etc. Mendeleev published the his Law in 1869 and was followed for long time.Mendeleev's periodic lawThe properties of elements are periodic functions of their atomic weights.But this model also had its own limitations. Still all respect the hard work behind the classification method. Later this classification model which had 8 groups was replaced by modern table with 18 groups prepared by Moseley.