Question

Write the formulae of chlorides of Eka-silicon and Eka-aluminium, the elements predicted by Mendeleev.

Answer 1

Mendeleev's Periodic Table

• Mendeleev established the renowned periodic law, which states that "element qualities are a periodic function of their atomic weight."
• Mendeleev organized elements according to their atomic weights in a table known as Mendeleev's Periodic Table.
• Elements with comparable qualities were grouped in vertical rows known as columns.
• The horizontal rows were referred to as periods.
• Mendeleev ordered the elements in the periodic table in ascending order of atomic mass, but when he couldn't locate an element with the expected qualities, he left a vacant spot for an element yet to be discovered and even anticipated the attributes of such elements. Example - Eka-boron and eka-aluminum.
• 

Eka-silicon

• Eka-silicon means one position below silicon.
• Mendeleev predicted the occurrence of an undiscovered element in the unoccupied position beneath silicon, thereby belonging to the same periodic table group IV B.
• C.A. Winkler of Germany later discovered and called this element germanium in 1886.
• It has valency $4$ since it belongs to a group $14$ of the modern periodic table.
• Chloride of Eka-silicon or germanium is ${\mathrm{GeCl}}_4$(Germanium tetrachloride)
• 

Eka-aluminium

• Eka-aluminium means one position below aluminum.
• Mendeleev predicted the occurrence of an undiscovered element in the unoccupied position beneath silicon, thereby belonging to the same periodic table group Iii B.
• C.A. Winkler of Germany later discovered and called this element gallium
• It has valency $3$ since it belongs to a group $13$ of the modern periodic table.
• Chloride of Eka-aluminium or gallium ${\mathrm{GaCl}}_3$(Gallium trichloride)
• $$\begin{gathered} {\mathrm{Ga}}^{3+}{\mathrm{Cl}}^{-} \\ \searrow \swarrow \\ \mathrm{Valency}=31(\mathrm{swap}\mathrm{the}\mathrm{valency}\mathrm{to}\mathrm{write}\mathrm{chemical}\mathrm{formula}) \\ ={\mathrm{GaCl}}_3 \end{gathered}$$