What is the oxidation number of carbon monoxide?

1 Answer
Nov 1, 2015

Answer:

Zero.

Explanation:

You need to consider the Lewis structure of carbon monoxide. Based on their group numbers in the periodic table, the valence electrons of #C# atom is 4 while for #O# atom, it is 6. So the sum of valence electrons is 10.

Drawing the electron dot structure of carbon monoxide,

https://www.youtube.com/watch?v=lEpfplRxcSg

Notice that the structure is sharing 6 electrons (2 from #C# atom and 4 from #O# atom), creating a triple bond between the elements.

Now if you count the number of electrons per element, you would notice that there are formal charges produced in this chemical bonding.

http://www.ebi.ac.uk/chebi/advancedSearchFT.do?structureSearchMethod=similarity&chebiId=15343

Although both atoms have a formal charge, the overall charge is still zero.

#CO# = (-1) + (+1) = 0

Incidentally, the #CO# molecule exists in three resonance forms but, as always the case, the one with the lowest value of overall formal charge is the most stable one.

https://commons.wikimedia.org/wiki/File:Carbon-monoxide-resonance-2Dpng