How about the following statement: :"Both the red color of Mars and the red color of blood are caused by an interaction of oxygen and iron." That avoids the term "oxidization" which is not involved in hemoglobin if I understand it correctly. --AxelBoldt |
Yeah I think this is correct. Oxygen is bound to the Haem groups in haemoglobin chains to form oxyhaemoglobin (HbO?8:
Hb + 4O2 -> HbO8?
Although 'oxidized' may not be so chemically correct (I don't know about loss of electrons) they are loosely bound and not in the 02 form.
The color of an ion depends on its environment. In aqueous solution ferric irons (Fe3+) are coordinated with six water molecules and have a yellow color rather than the reddish color of hematite, where they are coordinated with six oxide ions, while the anhydrous chloride is greenish. Fe2+ are green in aqueous solution but that doesn't say much, the presence of nitrogen and oxygen (only oxyhemoglobin is bright red) are going to affect the color significantly. The iron is definitely what is responsible, though, and most brightly colored compounds are made so by coordinated transition metals. Someday we should have an article on [ligand field theory]?.