The traditional physical system of chemical elements is displayed on one of the staff shown below 2D animation, gnomon modules for which are taken, as it is easy to see, from 3D model.

Figure 19. The traditional long form of the periodic system resulting from two-dimension symmetric transformations. 

The advantages and disadvantages of the indicated 2D model can be discussed. We would only like to note that the squares placed one on another are very simple and easy to remember. 

It should be noted that the same principle of build-up (composition) we can find in the literature. For example, the latin saying:

The valid friend is learnt by love, custom, transactions, things. 

The other example is immortal "Beacause" of "The Beatles":