text: CO contains a coordinate covalent bond which allows it to bond with hemo(globin?) in much the same way O2 does, which also contains those bonds. \nCO2, is more stable and unreactive since it contains 2 double bonds. \nLewis structures show these different bonds by showing the sharing of the valence electrons among between the atoms of the CO molecule. Since simply sharing 2 of carbons 4 valence electrons completes the octet of the oxygen atom, it is satisfied. But the carbon atom is left, at this point, lacking two to comlete its octet. Other electrons "help out" to complete the process, but make for an unstable configuration, allowing the CO molecule to bond effectively with other molecules.