What are oxidation states in elements?

1 Answer
Aug 21, 2016

Answer:

The oxidation state of an ELEMENT is #"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(s) + O_2(g) rarr CO_2(g)#

In the product, the oxidation state of #C# is #+IV#; the oxidation state of #O# is #-II#. 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:

#Fe(s) rarr Fe^(3+) + 3e^-#

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