Question

What are the oxidation numbers of copper? Give example

Answer 1

The different oxidation numbers of copper metal can be determined by calculating its individual oxidations numbers in its various compounds. Remember that copper is a transition metal and can show a variety of oxidation states, keeping in mind its electronic configuration.

Complete answer:
The process of oxidation requires a chemical species to lose one or more electrons or bind itself to oxygen atoms. It is a type of chemical reaction.
The oxidation numbers assigned to elements depend upon their bonding situation with other elements. It is a hypothetical number that indicates the number of electrons being lost or gained (involved in bond formations) by a particular element.
Copper is a transition metal belonging to the eleventh group of the d-block. Being a transition metal, it is capable of showing a variable oxidation state i.e. its oxidation state changes with each complex or compound it is a part of. The electronic configuration of copper is $4{s^1}3{d^{10}}$ i.e. it has a single electron filled in the s-orbital and ten electrons filled in the d-orbital (completely filled d-orbital).
Copper in its pure metallic form does not show any involvement of electrons and therefore has $0$ oxidation state.
Since losing a single electron by copper would lead to a fully-filled stable electronic configuration of $3{d^{10}}$ , copper is found in its $+ 1$ oxidation state.
Though losing two electrons would destabilize the electronic configuration of copper, John teller distortion, hydration enthalpy and various other factors are responsible for stabilizing copper in its $+ 2$ state.
Thus the oxidation numbers shown by copper are: $0, + 1{\text{ and }} + 2$
Example of copper compound in different oxidation states are as follows:
$0 \to$ copper metal
$+ 1 \to CuCl,C{u_2}{\text{O and }}C{u_2}S$
$+ 2 \to CuC{l_2},Cu{\text{O and }}CuS{O_4}$

Note:
Oxidation numbers of copper can be extended beyond $+ 2$ but such high oxidation states can be stabilized only in coordination complex and not normal compounds. The oxidation state of $+ 3$ is found in complexes like ${K_3}Cu{F_6}$ and $+ 4$ is found in $C{u_2}Cu{F_6}$.