Question

State modern periodic law.

Answer 1

Hint: Dmitri Mendeleev and Lothar Meyer developed the periodic law in 1869, independently. First periodic table was created by Mendeleev and it was then shortly followed by Meyer. Both of them arranged the chemical elements in order of their mass and they proposed that certain properties recur periodically.

Complete answer:
Modern periodic law actually states that the properties/characteristics of the elements are the periodic functions of their atomic numbers.
In a "periodic table", atoms are actually arranged in the order of their atomic numbers, chemical properties and electronic configuration. The seven rows in "periodic table" are referred to as periods. Earlier in older days, periodic law was followed by the function of the element’s atomic masses. The older periodic law was proposed by Mendeleev according to which the properties/characteristics of the elements are the periodic functions of their atomic masses rather than atomic numbers.
Followed by Mendeleev, Meyer proposed "modern periodic law" according to which, the physical or chemical properties/characteristics of the chemical elements are the periodic functions of their atomic numbers. In the modern periodic law, atomic number was taken into consideration in lieu of the easy understanding regarding the properties of elements.
The "modern periodic table" is also called the long form of the periodic table.

Note:
Periodic law is considered as one of the chemistry’s most significant concepts. While dealing with the elements, their characteristics, and their chemical reactions, chemists make use of the Periodic Law. The development of the modern periodic table was driven by the periodic law.