Question

Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
(a) Name the elements which have taken the place of these elements
(b) Mention the group and the period of these elements in the Modern Periodic Table.
(c) Classify these elements as metals, non-metals or metalloids
(d) How many valence electrons are present in each one of them?

Answer 1

(a) Eka-silicon was replaced by Germanium and Eka-aluminium was replaced by Gallium.
(b) Gallium: Group 13 Period 5
Germanium: Group 14 period S
(c) Gallium is metal, while Germanium is metalloid
(d) Gallium has 3 valence electrons, while Germanium has 4.