What do you understand by the term periodicity? Does the periodicity in properties is a function of

What do you understand by the term periodicity? Does the periodicity in properties is a function of valence electrons? Illustrate.

Answer – When the elements are arranged in order of increasing atomic numbers, elements with similar chemical properties are repeated at definite intervals. This is known as periodicity. Yes, this periodicity is due to the periodicity in the number of electrons in the outermost shell of the atoms of the elements. If elements having the same number of valence electrons are grouped together, the elements falling within each group are similar in chemical properties.