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?

Explanation

a] Eka-silicon was later identified as Germanium (Ge) and Eka- aluminium was named as Gallium (Ga)
b] Germanium (Ge) - Group 14, period 4, Gallium (Ga) - Group 13, period 4.
c] Gallium (Ga) is a metal while Germanium (Ge) is a metalloid. Gallium is placed in the 13th group: so there must be 13 - 10 = 3 valence electrons. Similarly germanium is placed in group 14: so there must be 14 - 10 = 4 valence electrons.