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?

(a) Gallium is the element that has taken the place of eka-aluminium.
Germanium is the element that has taken the place of eka-silicon.

(b) Gallium and Germanium are placed in the 4th period of the periodic table.
Gallium belongs to group 13 whereas Germanium belongs to group 14 in the periodic table.

(c) Gallium is metal whereas Germanium is a metalloid.

(d) Gallium has 3 valence electrons in its atom whereas germanium has 4 valence electrons.

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