The positions of the elements La, Ac, Lu, and Lr in the WebElements periodic table is justified in the article by William B. Jensen, J. Chem. Ed., 1982, 59, 634.

Elements 117, and 118 are not known at the time of writing, but are shown "greyed-out" in the tables at their expected positions for information.

In the standard form of the periodic table the s-block, p-block, and d-block elements are organised into 18 vertical columns called groups. These are labelled from 1 to 18 under current IUPAC numenclature.

Earlier labelling schemes (Trivial Group names)

For historical reasons some Groups have special names. Terms such as the "alkali metals" are in very common use whereas the term "pnictogens" is very much less common. Some of these special names are listed in the Table.