Main group elements, also known as representative elements, are found in groups 1-18 (formerly groups IA-VIIIA) of the periodic table. They are characterized by having valence electrons in the outermost energy level and exhibit a wide range of properties. Alkali metals (group 1) are highly reactive and form 1+ ions, while alkaline earth metals (group 2) are less reactive and form 2+ ions. Elements in groups 13-18 generally exhibit variable oxidation states and can form covalent bonds. Halogens (group 17) are highly reactive and form 1- ions, while noble gases (group 18) are unreactive due to their stable electron configurations.
