sentences: sodium belong to alkali metals , group 1 on the periodic table
docs: sodium is metallic_element. sodium is alkaline_metal. group_2_elements is alkaline_earth_metals. sodium_chloride is salt. gaseous_sodium is sodium. sodium_ion is sodium_atom. one_of_chemical_elements is sodium. salt is sodium_chloride. sodium_atom is atom. group_1_elements is alkali_metals.