Chart that arranges the chemical elements in rows and…

Chart that arranges the chemical elements in rows and columns according to their atomic number and recurring properties. Its first recognised version was published in 1869 by the Russian chemist Dmitri Mendeleev, who left gaps for undiscovered elements, such as gallium and germanium, and predicted their properties. Its eighteen groups include the alkali metals, the halogens and the noble gases. It now lists 118 confirmed elements, from hydrogen to oganesson.

The answer in 13 letters