Explanation:Modern Periodic Table:It is a classification of elements that are based on their atomic numbers.It states that the periodic properties of elements are a periodic function of their atomic numbers.The modern periodic table is based on Mendeleev's periodic table.It is prepared by Neils Bohr.s-Block Elements:- The elements in whose last electron enters the s- subshell is known as s-block elements.Group 1:Group 1 of the S-Block elements consists of Li, Na, K, Rb, Cs, Fr.The general electronic configuration of the elements is ns0-1.The elements of group 1 are known as the alkali metal.Group 2:Group 2 of the S-Block elements consists of Be, Mg, Ca, Sr, Ba, Ra.The general electronic configuration of the elements is ns0-2.The elements of group 1 are known as alkaline earth metals.Here, The set of elements belonging to the s-block is Na, Ca, Ba, Ra.