Question

Describe the main features of Mendeleev’s periodic table.

Answer 1

Hint: We know that the periodic table was first classified based on the atomic masses. Then, the modern periodic table was classified based on the atomic number.

Complete step by step answer:
Now, let’s first discuss why the classification of elements is very necessary for making the study easy. The early attempts in the classification of elements lead to the grouping of identified elements as metals and non-metals. The first attempt was put forward by Dobereiner; he grouped the elements into three triads. The second attempt was done by Newlands; he gave the law of octaves.
A Russian chemist whose name is Dmitri Ivanovich Mendeleev gave the most vital classification and contributed towards the development of a periodic table. According to him, the elements were arranged in order of their fundamental property which is the atomic mass and the similarities in the chemical properties of elements.
He was able to arrange only sixty-three elements which were known at that time. He left some blank spaces for the predicted elements which were not yet discovered at his time. There are eight groups in his periodic table. He arranged elements in periods (the horizontal rows) in the order of increasing atomic masses. The groups (the vertical columns) have elements that possess similar properties.
The modern periodic table was put forward by Henry Moseley. He arranged elements according to the most fundamental property that is the atomic number. Thus, accordingly the Mendeleev’s periodic table was modified and therefore named as Modern periodic table of elements.

Note:
Mendeleev classifies the arrangement of elements according to the atomic masses. However, in the modern periodic table the elements are classified according to the atomic number which was considered one of the best fundamental properties of elements.