Periodic table (detailed cells)
Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869. Mendeleev invented the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.
Periodic table of shapes
The periodic table of mathematical shapes is popular name given to a project to classify Fano varieties. The project was thought up by Professor Alessio Corti, from the Department of Mathematics at Imperial College London. It aims to categorise all three-, four- and five-dimensional shapes into a single table, analogous to the periodic table of chemical elements. It is meant to hold the equations that describe each shape and, through this, mathematicians and other scientists expect to develop a better understanding of the shapes’ geometric properties and relations.