Question

what is periodicity in properties of elements with reference to the modern periodic table? Why do all the elements of the same group have similar properties? How do the tendency of elements to gain electrons change as we move from left to right in a period? State the reason of this change​

Answer 1

Periodicity is the properties of element in the periodic table(increasing atomic no.)
All element of same group have similar property beacause its easy to study a group and all the other element also be studied

This is the only reason for change in gain electron ;> are ==> To better understanding of table

Answer 2

In the periodic table the chemical properties of an element are repeated or found again after regular intervals this is called periodicity. All the elements of the same group have same chemical properties due sme valency.i.e.they have same no. of electrons in the valence shell. Tendency of an element to gain electron on moving from left to right in a period increases due to decrease in the metallic characters.