Question

Copper forms two Chlorides $\mathrm{CuCl}$ and ${\mathrm{CuCl}}_2$ (1) Identify the Copper ions in these compounds? (2) What is the valency of Copper in each of these compounds? (3) By writing the sub-shell electronic configuration of Copper, find out a sub-shells from which the electrons are lost to form these ions. (4) Write the period and group to which Copper belongs. (Hint: Atomic number of Copper $=29$)

Answer 1

Given:

• Copper forms two Chlorides $\mathrm{CuCl}$ and ${\mathrm{CuCl}}_2$
• The atomic number of Copper $=29$

The Copper ions in the $\mathrm{CuCl}$ and ${\mathrm{CuCl}}_2$ compounds:

• The total charge on the compound $\mathrm{CuCl}=0$ and the number of Chlorine atoms is 1 for which the general valency is $-1.$
• Hence, the charge of Copper in the $\mathrm{CuCl}$ compound can be calculated as :

$$\begin{gathered} \mathrm{x}+(-1)=0 \\ \Rightarrow \mathrm{x}=+1 \end{gathered}$$

• Similarly, the total charge on ${\mathrm{CuCl}}_2$$=0$ and the number of chlorine atoms is 2 for which the general valency is $-1.$
• So the charge of Copper in the ${\mathrm{CuCl}}_2$ compound can be calculated as :

$$\begin{gathered} \mathrm{x}+(-1)\times 2=0 \\ \Rightarrow \mathrm{x}=+2 \end{gathered}$$

• Hence, the ions formed for compounds $\mathrm{CuCl}$ and ${\mathrm{CuCl}}_2$ are ${\mathrm{Cu}}^{+}\left(\mathrm{Cuprous}\right)\mathrm{and}{\mathrm{Cu}}^{2+}\left(\mathrm{Cupric}\right)$respectively.

The valency of copper in each of these compounds:

• As the central metal atom, Copper is surrounded by one Chlorine atom, hence the valence of $\mathrm{CuCl}$ $=1$
• Also, as the central metal atom, Copper is surrounded by two Chlorine atoms, hence the valence of ${\mathrm{CuCl}}_2$$=2$

Sub-shells from which the electrons are lost to form these ions:

• Copper has $29$electrons in its neutral form and has the d subshell electrons.
• The electronic configuration of copper is given as : $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{10}4{\mathrm{s}}^1$.
• Here the Configuration ${\mathrm{Cu}}^{+}$ ion is given as : $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^{10}$, which suggests the electrons are lost from the $4\mathrm{s}$ subshell.
• Similarly, the configuration ${\mathrm{Cu}}^{+2}$ ion is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}3{\mathrm{d}}^9$ which suggests the electrons are lost from the $3\mathrm{d}$ subshell.

The period and group to which copper belongs:

• Copper belongs to the fourth period.
• And it also belongs to the eleventh group.