Question

In Mendeleev’s periodic table elements are arranged their atomic number.

Answer 1

Hint: The modern periodic table was based on the atomic number. Mendeleev considered atomic masses as the periodic properties of elements.

Complete step by step answer:
Periodic table is the table in which the elements are arranged according to their properties. The first-ever periodic table was given by the scientist Mendeleev.
In Mendeleev periodic table atoms are arranged in increasing order of their atomic masses and chemical property. During that time only 63 elements were known. After studying the properties of these elements Mendeleev arranged the elements. When he arranged the elements in order of increasing atomic mass he observed that the properties repeat after a certain interval. According to this table he states the periodic law as “the properties of the elements are the periodic function of their atomic masses”. The vertical columns were named as groups and the horizontal rows were named as the period.
This was a good thing in the Mendeleev periodic table that some space was left for the elements that are yet to be discovered and when these elements were discovered later on they were found to be completely fit in those gaps. The demerits of Mendeleev periodic table was that he did not specify the position of hydrogen in the periodic table and the position of isotopes was also contrary to the Mendeleev periodic law.

Hence, the given statement is false.

Note:
The amendments were made in the Mendeleev periodic table and the modern periodic table was formed which we use today. The position of isotopes was also clear in modern periodic tables as it was based on atomic numbers. So the isotopes can be placed together but in the Mendeleev periodic table it was not possible to put them together.