Question

Why is the periodic table called a periodic table?

Answer 1

Hint: Periodic table is the table which classifies all the known elements in accordance to their properties in such a way that elements with similar properties are grouped together in the same vertical column and elements with different properties are separated from one another.

Complete answer:
It was found out by a Russian Chemist Dmitri Mendeleev that when the elements are arranged in order of their increasing atomic weights, elements with similar properties are repeated after certain regular intervals. The elements of the table exhibit periodicity which gave it the name Periodic Table.
The modern periodic law states that properties of the elements are periodic functions of their atomic numbers.
Periodicity arises because there is repetition of similar outer electronic configuration of elements at specific regular intervals.
We can say that the table is called Periodic Table because it exhibits periodicity.
The long form of periodic table consists of eighteen vertical columns known as Groups of periodic table and seven horizontal rows known as periods of periodic table. These have been obtained by arranging the elements in order of increasing atomic numbers in such a way that the elements with similar electronic configuration are placed under each other in the same vertical column.

Additional Information-: Mendeleev was the first one to fully recognize the significance of periodicity of properties of elements when arranged in increasing order of atomic weight. In spite of many advantages, Mendeleev’s table suffers from many defects. Later, it was found that atomic number is the better fundamental property of an element than atomic weight. Thus, the atomic number became the basis of classification of elements in the periodic table.

Note:
The position of Hydrogen in the modern periodic table is not completely justified. Also, the Lanthanide series and Actinide series have not been accommodated in the main body of the periodic table. These can be some defects of the modern periodic table.