How do you find the oxidation number of one element?

1 Answer
Aug 26, 2016

Answer:

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.