What is a periodic property? How the following properties vary in a group and in a period? Explain
(b) EN.

Explanation

Periodic property :Periodicity means that when elements are arranged accoding to their electronic configuratiin , the properties of elements in the perioodic table reoccr at regular intervals - such properties which reoccur are called called as periodic properties
change of properties in a group and a period :

Electronegativity : the electronegativity of an element is defind as the relative tendency of its atom to attract electrons towards irself when it is bounded to the atom of another element .
Variation in groups and periods : electronegativity values of elements decrese as we go down in a group and increase along a period from left to right .