Mendeleev gave temporary names for the undiscovered elements. He used the prefixes eka-, dvi- and tri- and combined it with any known elements in the same group with the undiscovered element. Eka-, dvi- and tri- are numbers 1, 2 and 3 in the Sanskrit language. The use of the prefix depends on how far the known element is from the unknown element. For example, germanium was called eka-silicon because silicon is placed one row above germanium, and rhenium was called dvi-manganese because manganese is placed two rows above rhenium. The names of these elements were changed after they were discovered.