Question

Define Modern Periodic Law. What is Periodicity and what is its Cause?

Answer 1

Dear student,

Modern periodic law: It states that properties of elements are a periodic function of their atomic number.

The trend of similar properties that are observed in elements, when arranged or positioned with increasing order of atomic number called periodicity.

The cause for the periodicity is the valence electrons of elements. Valence electrons influence the properties of elements. When elements are arranged in the order of increasing atomic number, then elements with the same number of valence electrons are grouped together. Members of same group have same electronic configuration and hence the same valency. Thus, members of a group show similar chemical properties, because of which they show periodicity.

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