Periodicity example sentences

It is then easy to visualize the significance of quantum numbers and electronic configureurations in periodicity of elements.They are of different types depending upon their periodicity.But why do the properties of elements follow these trends? And how can we explain periodicity? To answer these questions, we must look into the theories of atomic structure and properties of the atom.There is some periodicity in valence, for example, among representative elements, the valence is either equal to the number of electrons in the outermost orbitals or eight minus this number.He fully recognized the significance of periodicity and used broader range of physical and chemical properties to classify the elements.We know by now that the periodicity is related to electronic configureuration.