"Properties of elements are periodic function of their atomic number" Justify the statement with appropriate examples.
This statement means that when elements are arranged in increasing order of their atomic numbers, similarities in properties of the elements appear at regular intervals. For example: The electronic configuration of the elements repeats itself after a regular interval and thus elements with same electronic configuration are grouped in the same group. In a group, the elements have same number of valence electrons and thus similar chemical properties.The elements in group I are strongly metallic and electropositive as they form monovalent ions such as Na+, Li+, K+ etc. readily. Similarly, elements of group 17 have 7 valence electrons and are highly reactive.