Question

what is meant by periodicity of properties of elements? why are properties of elements placed in the same group of the periodic table similar?

Answer 1

Same group elements show same propertyies suchas they have same class such as they are all Ali metals or alkali gr or they are halogens

Answer 2

Answer:

The periodic repetition of the properties is due to the recurrence of similar valence shell configuration after certain regular interval.   So, because the elements in a group have similar electronic configuration, they have same number of valence electrons and therefore they show similar chemical properties.

Explanation: