“Mendeleev arranged elements in horizontal rows and vertical columns of a table in order of their increasing atomic weights".
“The elements in a Mendeleev periodic table with similar properties occupied the same vertical column or group”.
Eka-Aluminium:
Both Gallium and Germanium were not known at the time Mendeleev published his Periodic Table.
“Eka” in Sanskrit is used to define the number one. He named it Eka means next because he believed that the elements will be similar to aluminum, boron, and silicon.
He left the gap under Aluminium and named it Eka-Aluminium and a gap under Silicon and named it Eka-Silicon.
He named Eka-Aluminium which was named Gallium later and Eka-Silicon was named Germanium after.