Alternative periodic tables



Alternative periodic tables are chemical element displays different from the well known Mendeleev periodic table. Several have been devised often purely for didactic reasons as not all correlations between the chemical elements are effectively captured by the standard periodic table. The definitive work is Mazurs.

In Theodor Benfey's periodic table (1960) the elements spiral out in two dimensions starting from hydrogen folding their way around two islands, the transition metals & lanthanides and actinides. A superactinide island is already slotted in. In the Chemical Galaxy (2004) the elements spiral out in a similar way.

In the Extended periodic table, suggested by Glenn T. Seaborg in 1969,  yet unknown elements are included up to atomic number 218. Helium is placed in the group 2 elements Timmothy Stowe created the physicist's periodic table. This table is three-dimensional and the three axes represent the principal quantum number, orbital quantum number, and orbital magnetic quantum number. Helium is again a group 2 element.

Paul Giguere's 3-D periodic table consists of 4 billboards with the elements written on the front and the back. The first billboard has the group 1 elements on the front and the group 2 elements at the back with hydrogen and helium omitted altogether. At a 90° angle the second billboard contains the groups 13 to 18 front and back. Two more billboard each making 90° angles contain the other elements.

In the research field of superatoms, clusters of atoms have properties of single atoms of another element. It is suggested to extend the periodic table with a second layer to be occupied with these cluster compounds. The latest addition to this multi-story table is the aluminum Al7- cluster which behaves like a multivalent germanium atom

In a commentary R.L. Rich proposes a periodic table where elements appear more than once when appropriate. He notes that hydrogen shares properties with group 1 elements based on valency, with group 17 elements because hydrogen is a non-metal but also with the carbon group based on similarities in chemical bonding to transition metals and a similar electronegativity. In this rendition of the periodic table carbon and silicon also appear in the same group as titanium and zirconium.

Aims
Alternative periodic tables are developed often to highlight or emphasize different chemical or physical properties of the elements which are not as apparent in traditional periodic tables. Some tables aim to emphasize both the nucleon and electronic structure of atoms. This can be done by changing the spatial relationship or representation each element has with respect to another element in the table. Other tables aim to emphasize the chemical element isolations by humans over time.