Group I elements are called alkali metals. Group I consist of elements like Lithium ( Li ), Sodium ( Na ), Potassium ( K ), Rubidium ( Rb ), Caesium ( Cs ) and Francium ( Fr ).The group lies in the s- block of the periodic table. Alkali metals are abundant in minerals and sea water. They are named from the Arabic word "Alquili" meaning 'plants ashes'. Ashes of plants composed mainly of sodium and potassium.