What is the name of the arrangement of chemical elements that Mendeleev systematized?

The arrangement of chemical elements that Mendeleev systematized is called the periodic table.

The periodic table organizes elements into rows called periods and columns called groups. Elements in the same group often have related chemical properties because their atoms have similar patterns of outer electrons. The table therefore does more than list elements: it reveals recurring chemical behavior, known as periodicity.

Mendeleev's first widely recognized table appeared in 1869. He arranged elements largely by relative atomic weight and deliberately left gaps where he believed undiscovered elements belonged. He even predicted properties for several missing elements; the later discoveries of gallium, scandium, and germanium helped establish the credibility of his system.

The modern periodic table differs from Mendeleev's version because elements are ordered by atomic number, or proton count, rather than atomic weight. Other phrases such as “elemental chart” or “atomic table” may sound understandable, but “periodic table” is the standard and canonical name.