Question

Mendeléev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.

1. Name the elements which have taken the place of these elements
2. Mention the group and the period of these elements in the Modern Periodic Table.
3. Classify these elements as metals, non-metals or metalloids
4. How many valence electrons are present in each one of them?

Answer 1

1. Eka-Silicon was replaced by germanium, Eka-aluminium was replaced by gallium in the Mendeleev's periodic table.
2. Germanium-group number 14 and 4th period.
   Gallium-group number 13 and 4th period.
3. Germanium is a metalloid and gallium is a metal.
4. Germanium has 4 electrons and gallium has 3 valence electrons.