Question

How do you find the oxidation number of one element?

Answer 1

The oxidation number of an element is generally `0`.

Explanation:

Oxidation state is formally the charge on an atom when it donates or accepts electrons. While this is a formal exercise it does have utility in the balancing of redox equations. Because elements have demonstrably not transferred electrons, they are assigned a `0` oxidation state; they are `"zerovalent"`.

The burning of coal and fossil fuels is certainly an example of a redox equation:

`"Coal is oxidized from 0 to +IV"`

`CrarrC^(+IV) + 4e^-`

`"Oxygen is reduced from 0 to -II"`

`O_2 + 4e^(-)rarr 2O^(2-)`

For both these redox equations mass and charge are balanced, as they must be. (Are they?)

Add them together to eliminate the electrons:

`C(s) + O_2(g) rarr CO_2(g)`

Both elemental reactants are zerovalent BEFORE electron transfer occurs.