Question

Name the elements whose compounds formed the basis of classification in Mendeleev's periodic table. Why did Mendeleev choose these elements?

How the formulae of these compounds had helped Mendeleev in deciding the position of an element in his periodic table?

Answer 1

Mendeleev created the Periodic Table of Elements, which organised the elements according to their atomic masses and chemical similarities. He considered the chemical formulas of the hydrides and oxides each element produces as one of its fundamental qualities for categorization.

He chose oxygen and hydrogen because they are particularly reactive and can combine with most elements to make compounds. The characteristics of each element were then written on one of the 63 cards he had taken (there were 63 elements found at the time). He put them in order of increasing atomic mass and noticed that similar elements would periodically recur. Based on this, he developed the periodic law, which asserts that an element's characteristics are a periodic function of its atomic mass. Therefore, Mendeleev made a wise choice in using compound equations as the foundation for determining an element's place in his table. These cause components with comparable chemical characteristics to be grouped together.