What physical and chemical properties of elements were used by Mendeleev in creating his periodic table? List two observations which posed a challenge to Mendeleev’s Periodic Law. NOTE- please give answer in a different or short way and don't copy paste from any website.

What physical and chemical properties of elements were used by Mendele

1.	What physical and chemical properties of elements were used by Mendeleev in creating his periodic table? List two observations which posed a challenge to Mendeleev’s Periodic Law. NOTE- please give answer in a different or short way and don't copy paste from any website.
Answer» The chemical property used was the nature of oxide and HYDRIDE FORMED i.e. SIMILARITY in chemical properties were used by Mendeleev. The two observations that posed challenge in Mendeleev Periodic Law were: i Arranging elements according to the INCREASING order of atomic mass COULD not be maintained I hope it helps you