Which type of data have elements in common but do not fit into rigid rows and columns in a table?.

Semi-structured data is a type of data that has some consistent and definite characteristics. It does not confine into a rigid structure such as that needed for relational databases that which is why  it will not fit into row and columns in a table .

Explanation:

each chemical family is represented as a group or column on the periodic table. based on chemical properties, there are 6 types of chemical families. group 1 represents alkali metals, group 2 represents alkaline earth metals, groups 3 to 12 represent transition metals, groups 13 to 16 represent non-metals and other metals, group 17 represents halogens and group 18 represents noble gases.