APA citation style: Historic American Buildings Survey, C. & Benison, G. (1933) Oakland Plantation, Mount Pleasant, Charleston County, SC. Documentation Compiled After. [Pdf] Retrieved from the Library of Congress, https://www.loc.gov/item/sc0292/.
There are 18 groups (columns) in the periodic table. Group 1 (also known as the alkali metals) is the column on the far left of the table. Elements in the same group have similar, but not identical characteristics. This is because they all have the same number of electrons in their outermost shell.
Just look in to the periodic table. Al is in group 3A and it means it is an element. Everything in the periodic table is element there is not compound or alloy or solution or anything else but elements in periodic table. Periodic table is the best cheat sheet of the world!