Question

Illustrate by taking examples of transition elements and non-transition elements that oxidation states of elements are largely based on electronic configuration.

Answer 1

The electronic configuration of an element determines its oxidation state. The participation of $(n-1)d$ and outer $ns$ electrons in bonding results in the multiple oxidation states of a transition metal.

Non-transition elements, primarily p-block elements, can have a range of oxidation states ranging from $+n$ 𝑡𝑜 $(n-8)$, where $n$ denotes the number of electrons in the outermost shell. Phosphorus $(n=5)$, for example, can have oxidation states of $-3,+3,$ and $+5$.

Examples:

Alkali metals (Group$-1$):
General electronic configuration $=n{s}^1$
Oxidation state $=+1$

Alkaline Earth metals (Group$-2$):
General electronic configuration $=n{s}^2$;
Oxidation state $=+2$

Group $13$ elements:
General electronic configuration $=n{s}^{2}n{p}^1$;
Oxidation state $=+3$ and $+1$
Boron shows only $+3$ oxidation state in its compounds.

Group $14$ elements:
General electronic configuration $=n{s}^{2}n{p}^2$;
Oxidation state $=+4,+2$

Group $15$ elements:
General electronic configuration $=n{s}^{2}n{p}^3$
Oxidation states $=-3,+3$ and $+5$
Nitrogen $\left(N\right)$ also shows $+1,+2$ and $+4$ oxidation states.

Group $16$ elements:
General electronic configuration $=n{s}^{2}n{p}^4$
Oxidation states $=-2,+2,+4$ and $+6$
$O$ show $+2,-2,+1,-1$ oxidation states.

Group $17$ Elements:
General electronic configuration $=n{s}^{2}n{p}^5$
Oxidation state $=-1$
$Cl,Br$ and $I$ also show $+1,+3,+5$ and $+7$ oxidation states.

Group $18$ elements:
General electronic configuration $=n{s}^{2}n{p}^6$
Oxidation state $=0$

Transition elements (d-block elements)

General electronic configuration $=(n-1)d^{1-10}n{s}^{1-2}$
The elements show variable oxidation states.
The most common oxidation states are $+2$ and $+3$.
$Zn$ shows oxidation state of $+2$.
$Cr$ shows variable oxidation states: $+2,+3,+4,+5,+6$.