Give an account of the process adopted by Mendeleev ′ for the classification of elements. How did he arrive at “Periodic Law”?

During Mendeleev’s time, only 63 elements were known. Mendeleev examined the correlation between chemical properties and Atomic masses of elements. For this, he concentrated on compounds that were formed by the elements with hydrogen and oxygen. He selected hydrogen and oxygen, because these elements make a compound with most of the other elements.

Mendeleev made 63 cards and wrote the name of an element on each card: along with the chemical properties of a particular element. Then, he pinned those cards on a wall. He could observe that most of the elements could be arranged in the periodic table in increasing order of their atomic masses. That is how Mendeleev arrived at “Periodic law” which states that properties of elements are periodic function of their atomic masses.