# What are oxidation states in elements?

Aug 21, 2016

The oxidation state of an ELEMENT is $\text{ZERO}$

#### Explanation:

The oxidation state of an atom in a compound is the charge left on the atom when all the bonding pairs are broken, and the charged devolved to the most electronegative atom.

Given this, an element usually has a $0$ oxidation state because as an element it has neither donated nor accepted electrons.

We could start with a simple combustion rxn:

$C \left(s\right) + {O}_{2} \left(g\right) \rightarrow C {O}_{2} \left(g\right)$

In the product, the oxidation state of $C$ is $+ I V$; the oxidation state of $O$ is $- I I$. But the elements are zerovalent, $0$ oxidation state. Electron transfer is conceived to have occurred in the combustion process.

Metals provide a particularly rich redox chemistry. We would represent the oxidation of Fe to ferric ion as:

$F e \left(s\right) \rightarrow F {e}^{3 +} + 3 {e}^{-}$

Of course the electrons must go somewhere, and they typically reduce oxygen to give iron oxides, rust, the bane of structural engineers.