Alkali metals refer to the six metal elements of Group IA in the periodic table except hydrogen (H), namely lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and francium (Fr).
According to IUPAC, alkali metals belong to Group IA elements in the periodic table of elements. Alkali metals all have a outermost electron belonging to the s orbital, so this group belongs to the s region of the periodic table. The chemical properties of alkali metals show very obvious homologous behavior, which is the best example of the periodicity of elements. Although hydrogen (H) belongs to Group IA, its chemical properties are far different from those of alkali metal, so it is not considered as alkali metal.
