Question

19. What is meant by periodicity of properties of elements ? Why are the
elements placed in the same group of the periodic table similar ?​

Answer 1

Answer:

Periodicity is the repetition of elements with similar properties when they are arranged according to their atomic no. in the periodic table.

all elements of the same group have the similar properties because because they have similar outer electronic configuration. for example, in group 17 ,halogens have the electronic configuration ns^2 np^7 .

as we move from left to right, size decreases, nuclear charge increases and hence the electrons feel more attracted towards the atom and hence the tendency to gain electrons increases. Halogens (group 17 elements) are the most electronegative with Fluorine being the highest.