Question

What is the basic difference between Mendeleev's periodic table and the modern periodic table?

Answer 1

Hint: Genesis of periodic classification of elements into groups and development of periodic law and the periodic table. It is very necessary to classify elements to study the individual properties and a systematic way to organize their knowledge in searching elements.

Complete step by step solution:
Firstly Doberneir started the study of a periodic relationship after that Mendeleev was responsible for the first time-periodic table constructed and published the first periodic law as follows:
“the properties of the elements are a periodic function of their atomic weights”
After that Mendeleev's modified periodic law which identifies atomic number is more fundamental property than atomic mass and the modifies periodic law is named as Modern periodic law which states as follows:
“The physical and chemical properties of the elements are periodic functions of their atomic numbers”
This law modifies the Mendeleev's periodic table into the Modern periodic table. There are more differences between Mendeleev's periodic table and the modern periodic table given below.

Mendeleev's periodic table	Modern periodic table
This periodic table based on atomic mass	This periodic table is based on atomic numbers.
There are a total of 7 groups and 6 periods	There are a total of 18 groups and 7 periods.
Elements are arranged based on their increasing in atomic mass	Elements are arranged based on the increasing order of their atomic numbers.
There is no place allotted for isotopes	Isotopes are kept in the same place due to their atomic numbers being the same.

Note: Coinage metals of copper, silver, and gold are grouped in Mendeleev’s periodic table. Manganese metal allotted place in the halogen group. These defects are rectified by the modern periodic table. The fundamental property to distinguish each element in the modern periodic table is the atomic number which gives basic nature to decide the physical and chemical properties of elements than atomic weights.