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?

Mendeleev predicted the existence of certain elements not known at tha

1.	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?
Answer» Solution :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.