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